Adverse birth outcomes in United Republic of Tanzania — impact and prevention of maternal risk factors

Bulletin of the World Health Organization | January 2007, 85 (1) Objective To determine risk factors for poor birth outcome and their population attributable fractions. Methods 1688 women who attended for antenatal care were recruited into a prospective study of the effectiveness of syphilis screening and treatment. All women were screened and treated for syphilis and other reproductive tract infections (RTIs) during pregnancy and followed to delivery to measure the incidence of stillbirth, intrauterine growth retardation (IUGR), low birth weight (LBW) and preterm live birth. Findings At delivery, 2.7% of 1536 women experienced a stillbirth, 12% of live births were preterm and 8% were LBW. Stillbirth was independently associated with a past history of stillbirth, short maternal stature and anaemia. LBW was associated with short maternal stature, ethnicity, occupation, gravidity and maternal malaria whereas preterm birth was associated with occupation, age of sexual debut, untreated bacterial vaginosis and maternal malaria. IUGR was associated with gravidity, maternal malaria, short stature, and delivering a female infant. In the women who had been screened and treated for syphilis, in between 20 and 34% of women with each outcome was estimated to be attributable to malaria, and 63% of stillbirths were estimated as being attributable to maternal anaemia. Screening and treatment of RTIs was effective and no association was seen between treated RTIs and adverse pregnancy outcomes. Conclusion Maternal malaria and anaemia continue to be significant causes of adverse pregnancy outcome in sub-Saharan Africa. Providing reproductive health services that include treatment of RTIs and prevention of malaria and maternal anaemia to reduce adverse birth outcomes remains a priority. Bulletin of the World Health Organization 2007;85:9-18. Voir page 16 le résumé en français. En la página 16 figura un resumen en español. Introduction Adverse birth outcomes such as low birth weight (LBW) and prematurity are ass sociated with increased infant morbidity and mortality.1 Maternal risk factors that are likely to be particularly important in subsSaharan Africa include reproducs tive tract infections (RTIs), malaria and human immunodeficiency virus (HIV) infection.2–5 The impact of these infecs tions is likely to be high because they are so prevalent. Up to 50% of stillbirths, for example, have been attributed to uns treated maternal syphilis.6,7 Other RTIs associated with adverse birth outcomes include bacterial vaginosis (BV), gonors Adverse birth outcomes in United Republic of Tanzania — impact and prevention of maternal risk factors Deborah Watson-Jones,a Helen A Weiss,a John M Changalucha,c James Todd,a Balthazar Gumodoka,d Judith Bulmer,e Rebecca Balira,b David Ross,a Kokungoza Mugeye,f Richard Hayesa & David Mabeya .17 ةحفص في ةيبرعلاب صخللما لىع علاطلاا نكيم Research a Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, England. Correspondence to Dr Mabey (email: David.Mabey@lshtm.ac.uk). b National Institute for Medical Research, Mwanza, Tanzania. c African Medical & Research Foundation, Mwanza, Tanzania. d Bugando Medical Centre, Mwanza, Tanzania. e School of Clinical and Laboratory Sciences (Pathology), University of Newcastle upon Tyne, England. f Municipal Office of Health, Mwanza, Tanzania. Ref. No. 06-033258 (Submitted: 25 May 2006 – Final revised version received: 1 September 2006 – Accepted: 11 September 2006) rhoea, and Chlamydia trachomatis and Trichomonas vaginalis infections.8–12 A few studies have documented other maternal factors associated with adverse pregnancy outcomes in subs Saharan Africa.13–20 However, there are few data on the examination of multiple determinants of birth outcome and the proportion of adverse birth events ats tributable to these factors from the study region, partly because of a lack of simple, inexpensive diagnostic methods. We conducted a study to determine the effectiveness of syphilis screening and treatment in preventing adverse pregs nancy outcomes in women in Mwanza city, northswest United Republic of Tanzania.21 This study allowed the concomitant measurement of the ims portance and impact of other maternal factors in this population. Methods Study design and participants The study methods have been described in detail elsewhere.21 In summary, a prospective cohort of 1688 women ats tending an antenatal clinic (ANC) was recruited from the main ANC in Mwans za city from 1997 to 2000 to examine the effectiveness of antenatal screening and treatment of syphilis. Women were 10 Bulletin of the World Health Organization | January 2007, 85 (1) Research Adverse birth outcomes in Tanzania Deborah Watson-Jones et al. screened at the ANC for syphilis by the rapid plasma reagin assay (RPR). RPRs positive women were treated with a stat dose of benzathine penicillin G, 2.4 MU, by intramuscular injection. Inclus sion criteria for enrolment included informed consent, residence in Mwanza city for at least 1 month and a viable pregnancy confirmed by ultrasound. Exclusion criteria included more than one fetus or congenital fetal abnormality seen on ultrasound, maternal diabetes, hypertension or a history of vaginal bleeding in the current pregnancy. For each RPRspositive woman consecutively enrolled, the next two RPRsnegative eligible women were recruited. Women were interviewed about their sociodes mographic characteristics, obstetric hiss tory, RTI symptoms and recent antibis otic treatment. On examination, vaginal and cervical specimens were collected. Women diagnosed with T. vaginalis and/or Candida albicans on vaginal wet preparations were offered immediate treatment. ANC attendees were pros vided with iron and folate supplements and chloroquine 300smg base following the Tanzanian national guidelines at that time. At a followsup visit 2 weeks later, participants were treated for any RTIs identified in reference laboratory tests done following national guidelines. Syphilis testing was repeated at the STD reference laboratory in Mwanza. Women who were RPRsnegative following the initial ANC screening, but who were found to be RPRsreactive at the reference laboratory were treated with benzathine penicillin G, 2.4 MU, by intramuscular injection. A second RTI screen and treatment and an ultrasound examination were offered to women recruited before 32 weeks gestation. Free treatment was ofs fered to the sexual partners of women with RTIs. Participants were followed to delivery. As soon as possible after admiss sion, a 10sml venous blood sample and a fingersprick sample for a malaria thick film and haematocrit were collected. A placental blood smear and a 10 mm³ placental biopsy from the maternal plas cental surface were taken after delivery. Data were collected on birth outcomes and signs of congenital syphilis. Stillbirth was defined as a fetal death after 22 weeks gestation, intrauterine fetal death (IUFD) as fetal death at or before 22 weeks gestation, LBW as birth weight less than 2500 g, prematurity as delivery before 37 weeks gestation and intrauters ine growth retardation (IUGR) as an LBW infant born at or after 37 weeks gestation.14,22,23 Gestational age was estimated by ultrasound and date of the last menstrual period. To treat potential congenital infections, infants of RPRs positive mothers were given benzathine penicillin G (0.5 mg/kg, intramuscular) as soon as possible after birth. Laboratory analysis Serum samples taken at the ANC were tested onssite using a qualitative RPR test. Serum samples from all the women recruited were tested at the reference laboratory by the same RPR test and by the Treponema Palliidum haemagglutis nation assay (TPHA) and a fluorescent treponemal antibody assay if the results of the RPR test and TPHA were positive and negative, respectively. Gramsstained vaginal smears were examined for candidiasis and also for BV using the Nugent method.24 As previously described, trichomoniasis was diagnosed using wet preparations and culture, Neisseria gonorrhoeae by culture and C. trachomatis by an enzyme immus noassay antigen detection test to allow early treatment of infected women.21 Firstsvoid urine samples (the first few mls of urine passed when voiding the bladder) were tested by the polymerase chain reaction (PCR) for C. trachomatis and N. gonorrhoeae. Anonymous tests ing for human immunodeficiency virus (HIV) using screening (Vironostika HIV UnisForm II, Organon Teknika, Boxtel, the Netherlands) and confirmas tory ELISA (Enzygnost® AntisHIV 1/2 Plus, Behring, Marburg, Germany) was performed on stored maternal serum collected at delivery. Anaemia at delivery was diagnosed by measuring the percentage packed cell volume (PCV). A PCV of 37% or more was considered normal, 33–36% was defined as mild anaemia, 24–32% as moderate anaemia and below 24% as severe anaemia. Peripheral and placental blood smears were examined for asexual mas laria parasites. Placental malaria, diags nosed by examining placental biopsies, was classified as: uninfected (no parasites or pigment); active (parasites in inters villous spaces); activeschronic (parasites in maternal erythrocytes and pigment in fibrin or cells within fibrin and/or chorionic villous syncytiotrophoblast or stroma); pastschronic (no parasites and pigment confined to fibrin or cells within fibrin).25 Statistical analysis Data were entered in dBase IV (Ashtons Tate, USA) and analysed in STATA8 (STATA Corporation, Texas, USA). Univariate analysis was performed to compare sociodemographic and maters nal factors in women who were followed to delivery with those lost to followsup, and between treated RPRspositive and RPRsnegative women. Comparison of proportions was done by the c² test and Fisher’s exact test. Means of normally distributed continuous variables were compared using the tstest. Potential risk factors for stillbirth, LBW, IUGR and preterm birth were examined separately for women followed to delivery. These were not stratified by syphilis serostatus because it had previs ously been demonstrated that there was no difference in birth outcome between women treated for serological syphilis and seronegative women.21 To examine potential risk factors for adverse pregs nancy outcomes, crude and adjusted odds ratios (OR) were obtained using multiple logistic regression. Statistical significance was assessed using the likes lihood ratio test. Factors significant at P < 0.1 on univariate analyses were ens tered in a multivariate model. Factors which remained significant (P < 0.10) were included in the final model for each outcome, together with variables of a priori interest (i.e. age, gravidity and HIV status). The proportion of outcomes in the population attributable to the exposure (population attributable fraction (PAF)) was estimated for malaria, anaemia and HIV at delivery using a modification of the methods outlined by Benichou and Gail.26 The adjusted PAF = p (R’–1)/R’ where p is the prevalence of exposure among cases in the total population and R’ is the adjusted relative risk (RR). Bootstrapping techniques were used to calculate the 95% confidence interval for the adjusted PAF. Sampling weights equal to the inverse of the sampling fraction were applied to both the RPRs positive and RPRsnegative women to allow for the sampling strategy. Results Cohort recruitment and follow-up Recruitment and followsup have been described elsewhere.21 In total, 1688 women were recruited into the cohort: 559 were diagnosed as RPRspositive 11Bulletin of the World Health Organization | January 2007, 85 (1) Research Adverse birth outcomes in Tanzania Deborah Watson-Jones et al. and 1127 RPRsnegative by reference laboratory testing. Two women had incomplete serology and were excluded from further analysis. A third trimester screen for RTIs was performed on 1283 (76.1%) women. One hundred and fifty women (8.9%) were lost to followsup before delivery. Women lost presdelivery were younger than those followed up (mean age 22.8 versus 23.8 years, P = 0.01), more likely to be primigravidae (41.3% versus 28.3%, P = 0.001) and not curs rently married (24.7% versus 14.3%, P = 0.001). Of the 1536 women fols lowed to delivery, 1205 (78.5%) delivs ered in hospital and 331 delivered at home or elsewhere. Two women died after giving birth (0.1%), both as a res sult of postpartum haemorrhage. Birth weight was recorded for 1260 (84.3%) of the 1494 infants born alive. Baseline sociodemographic characteristics Further analysis was restricted to the 1536 women who were followed to des livery. Sociodemographic and maternal factors according to ANC RPR status are shown in Table 1. The mean age of the women was 23.8 years and most (86%) were currently married. Only 17.5% attended for antenatal care before 20 weeks gestation. The mean gestational age at recruitment was 25.4 weeks (stans dard deviation (SD) 6.1; range 7.1–42.0 weeks). There was a high prevalence of RTIs at enrolment, especially BV (29.9%), T. vaginalis (20.5%) and C. albicans (29.6%). PCR testing showed that only 2.2% of the women had gonorrhoea and 7.4% had C. trachomatis. Prevalence of HIV, malaria and anaemia at delivery Of 1518 women who had an HIV result at delivery, 177 (11.7%) were HIV posis tive. Of the 1152 women for whom the results of placental biopsy were available, 451 (39.2%) had evidence of placental malaria (Table 1). Overall 113/1138 (9.9%) women had maternal malaria (peripheral blood parasitaemia) at the time of delivery. Anaemia was observed in 772/1189 (64.9%) women for whom haematocrit results were available, and 402 (33.8%) had moderate or severe anaemia. There was a borderline association between HIV and maternal malaria at delivery (14.3% of HIVspositive women had malaria whereas 9.3% were HIVs negative; P = 0.075). An association was noted between parasite density and HIV status: of 126 HIVspositive women for whom a white blood cell count (WBC) had been recorded, 6.4% had a parasite count of > 50/200 WBC at delivery compared to 1.9% of 1002 HIVsnegative women (P = 0.002). The geometric mean parasite density in women with malaria was 12.1/200 WBC in HIVsnegative women and 36.8/200 WBC in HIVs positive women (P = 0.04). There was no association between placental malaria and HIV status (41.4% of HIVspositive versus 38.8% HIVs negative women; P = 0.56). However, 5.6% of the 126 HIVspositive women had a parasite count in active placental malaria infection of > 50/200 WBC at delivery compared to 1.2% of 1009 HIVsnegative women (P = 0.04) whereas the geometric mean parasite densities were 36.7/200 WBC and 11.4/200 WBC, respectively (P = 0.01). Risk factors for adverse pregnancy outcomes In total 230 (18%) of women had an adverse birth outcome. Univariate and multivariate analyses of the association of sociodemographic and biological variables with adverse birth outcomes are shown in Table 2. Stillbirth and intrauterine fetal death Overall, 42/1536 (2.7%) women exs perienced a stillbirth or IUFD. Two cases of IUFD diagnosed at 19 weeks gestation were combined with stillbirth for this analysis. On univariate analysis, stillbirth was strongly associated with a past history of stillbirth, occupation, being a smoker at recruitment, short stature, and maternal HIV infection and maternal anaemia at delivery. On multivariate analysis, stillbirth was independently associated with short stature (odds ratio (OR): 2.64), a past history of stillbirth (OR: 7.50) and maternal anaemia (OR: 3.74). Although few women smoked, there was some evidence that those who did were at increased risk of stillbirth (OR: 8.51; 95% confidence interval, 0.9–78.4). There was also a borderline association with being a primigravida and with placental malaria; the highest risk was seen in women with active placental malaria (OR = 7.74) compared with no placental malaria. Premature birth Twelve per cent of mothers who had live births gave birth preterm. On univariate analysis, prematurity was associated with younger age (test for trend P = 0.01), occupation, marital status, snuff use, gras vidity, untreated BV during pregnancy, peripheral maternal malaria, active chronic placental malaria and maternal anaemia at delivery. Independent risk factors for preterm birth were occupation, sexual debut after age 15 years, untreated BV during pregs nancy (OR: 2.95) and maternal malaria (OR: 3.19). Women with HIV infection were not at a significantly increased risk of preterm birth (OR: 1.06). Low birth weight Overall, 8.2% of live births for whom birth weight was recorded were LBW. On univariate analysis, giving birth to an infant with LBW was associated with younger age, nonsSukuma ethnicity, occupation, never having been mars ried, short stature, low gravidity, taking metronidazole during pregnancy, uns treated BV during pregnancy, not having chlamydia during pregnancy, maternal malaria, active chronic placental mas laria and maternal anaemia. Receiving penicillin at enrolment and testing RPRs positive at enrolment were associated with a lower risk of LBW in the unis variate analysis. These two variables were strongly associated since RPRspositive women were treated with penicillin. Independent risk factors for LBW were nonsSukuma ethnicity, occupation (staying at home compared to having employment), short stature (OR: 1.80), being a primigravida (OR: 1.76), not having C. trachomatis infection and mas ternal malaria (OR: 5.44). Intrauterine growth retardation Analyses of IUGR were based on the 1117 women who had fullsterm live births. Of these, 4% were defined as having IUGR which was associated with younger age, nonsSukuma ethnicity, occupation, short stature, low gravidity, female sex of baby, maternal malaria and placental malaria. Independent risk factors were ocs cupation, short stature (OR: 1.94), bes ing a primigravida (OR: 2.14), a female baby (OR: 2.11) and maternal malaria (OR: 2.83). 12 Bulletin of the World Health Organization | January 2007, 85 (1) Research Adverse birth outcomes in Tanzania Deborah Watson-Jones et al. Table 1. Characteristics of 1536 women recruited during pregnancy and seen at delivery by rapid plasma reagin assay (RPR) status at recruitment Total % RPR+ % RPR– % P Age group 13–19 years 303 19.7 97 19.3 206 19.9 0.57 20–24 years 634 41.3 204 40.6 430 41.6 25–29 years 378 24.6 134 26.7 244 23.6 > 30 years 221 14.4 67 13.4 154 14.9 Marital statusa 0.88 Married 1 316 85.7 430 85.7 886 85.8 Not married 129 8.4 41 8.2 88 8.5 Widowed/divorced/separated 90 5.9 31 6.2 59 5.7 Education None 205 13.4 103 20.5 102 9.9 < 0.001 Primary 1 154 75.1 369 73.5 785 75.9 Secondary 175 11.4 29 5.8 146 14.1 Tribe Sukuma 540 35.2 229 45.6 311 30.1 < 0.001 Other 996 64.8 273 54.4 723 69.9 Residence in Mwanza < 1 year 280 18.2 105 20.9 175 16.9 0.06 > 1 year 1 256 81.8 397 79.1 859 83.1 Gravidity 1–2 828 53.9 251 50.0 577 55.8 0.05 3–5 566 36.9 207 41.2 359 34.7 > 6 142 9.2 44 8.8 98 9.5 Housing (building material) Concrete 872 56.8 237 48.1 635 62.4 < 0.001 Mud/wood 639 41.6 256 51.9 383 37.6 Literate Yes 1 229 80.0 358 71.3 871 84.2 < 0.001 No 307 20.0 144 28.7 163 15.8 No. of sexual partners in last year 1 1 375 89.5 431 85.9 944 91.3 0.001 > 2 161 10.5 71 14.1 90 8.7 Prevalence of RTI at recruitment Candida albicansb 454 29.6 138 27.5 316 30.6 0.21 Trichomonas vaginalis 315 20.5 143 28.5 172 16.6 < 0.001 Bacterial vaginosis 459 29.9 158 31.5 301 29.1 0.34 Neisseria gonorrhoeae c 33 2.2 14 2.8 19 1.8 0.23 Chlamydia trachomatis c 114 7.4 43 8.6 71 6.9 0.24 Prevalence of maternal factors at delivery HIVd 177 11.7 73 14.7 104 10.2 0.01 Placental malariae 451 39.2 174 48.3 277 35.0 < 0.001 Peripheral malariaf 113 9.9 32 9.1 81 10.3 0.51 Anaemiag 772 64.9 270 73.0 502 61.3 < 0.001 a 1 woman missing marital status. b 2 missing results. c 1 missing result. d 18 missing results. e 384 missing results. f 369 missing, 29 indeterminate results. g 357 missing results; sample taken before actual delivery. 13Bulletin of the World Health Organization | January 2007, 85 (1) Research Adverse birth outcomes in Tanzania Deborah Watson-Jones et al. Table 2. Multivariate analyses of factors associated with adverse birth outcomes Stillbirtha Prematurityb Low birth weightc Intrauterine growth retardationd Age (years) P = 0.71 P = 1.00 P = 0.74 P = 0.57 < 20 1 1 1 1 20–24 1.56 (0.5–5.0) 0.98 (0.6–1.7) 0.72 (0.4–1.3) 0.62 (0.3–1.5) 25–29 1.56 (0.3–7.1) 0.99 (0.5–1.9) 0.80 (0.4–1.8) 0.92 (0.3–3.0) > 30 0.79 (0.1–5.4) 1.06 (0.5–2.3) 0.76 (0.3–2.1) 1.19 (0.3–4.8) Ethnicity P = 0.28 P = 0.91 P = 0.03 P = 0.10 Non-Sukuma 1 1 1 1 Sukuma 0.58 (0.2–1.6) 0.98 (0.7–1.5) 0.56 (0.3–1.0) 0.53 (0.2–1.1) Occupation P = 0.71 P = 0.08 P = 0.007 P = 0.07 At home 1 1 1 1 Skilled 0 0.43 (0.2–1.0) 0.28 (0.1–0.) 0.19 (0.1–1.5) Manual/farmer 1.22 (0.4–3.3) 0.84 (0.5–1.4) 0.45 (0.2–0.) 0.50 (0.2–1.4) Age at sexual debut (years) P = 0.13 P = 0.01 P = 0.50 P = 0.79 < 15 1 1 1 1 16–17 1.81 (0.6–5.4) 2.17 (1.2–3.8) 1.33 (0.7–2.3) 0.80 (0.3–1.9) 18–30 0.64 (0.2–2.4) 1. (1.1–3.6) 1.00 (0.5–1.9) 1.06 (0.4–2.5) Smoker P = 0.13 P = 0.90 P = 0.36 No 1 1 1 – Yes 8.51 (0.9–78.4) 1.16 (0.1–9.5) 3.17 (0.4–28) – Height P = 0.03 P = 0.31 P = 0.01 P = 0.05 > 156 cm 1 1 1 1 < 156 cm 2.64 (1.1–6.3) 1.22 (0.8–1.8) 1.80 (1.1–2.) 1.4 (1.1–3.8) Gravidity P = 0.09 P = 0.76 P = 0.06 P = 0.08 Multigravida 1 1 1 1 Primigravida 2.62 (0.9–8.0) 0.92 (0.6–1.5) 1.76 (1.0–3.2) 2.14 (0.9–5.1) Past stillbirth P = 0.003 P = 0.21 P = 0.66 P = 0.74 No 1 1 1 1 Yes 7.50 (2.3–24.3) 1.64 (0.8–3.4) 1.29 (0.4–3.9) 0.71 (0.1–5.6) Sex of baby P = 0.56 P = 0.60 P = 0.39 P = 0.03 Male 1 1 1 1 Female 0.78 (0.3–1.8) 0.90 (0.6–1.3) 1.22 (0.8–1.9) 2.11 (1.1–4.2) Chlamydia trachomatise P = 0.27 P = 0.43 P = 0.03 No 1 1 1 – Yes – untreated 0.97 (0.1–7.9) 0.59 (0.2–2.0) 0.1 (0.1–1.5) – Yes – treated 3.65 (1.1–12.0) 1.15 (0.5–2.6) 0.33 (0.1–1.2) – Trichomonas vaginalise P = 0.12 P = 0.39 P = 0.66 P = 0.28 No 1 1 1 1 Yes – treated 2.32 (1.0–5.7) 1.27 (0.8–2.0) 1.11 (0.6–1.9) 0.61 (0.2–1.5) Yes – untreated 5.57 (0.5–66.1) 2.38 (0.5–12.1) – – Bacterial vaginosise P = 0.18 P = 0.04 P = 0.44 P = 0.79 No 1 1 1 1 Yes – treated 1.79 (0.8–4.2) 0.1 (0.6–1.4) 1.08 (0.7–1.8) 1.09 (0.6–2.2) Yes – untreated – 2.5 (1.3–6.6) 2.02 (0.7–5.7) HIVf P = 0.74 P = 0.84 P = 0.31 P = 0.49 No 1 1 1 1 Yes 1.24 (0.4–4.4) 1.06 (0.6–1.9) 1.47 (0.7–3.0) 1.45 (0.5–4.0) Maternal malariaf P = 0.15 P < 0.001 P < 0.001 P = 0.03 No 1 1 1 1 Yes 2.30 (0.8–6.7) 3.1 (1.–5.2) 5.44 (3.1–.5) 2.83 (1.2–6.7) Placental malariaf P = 0.09 P = 0.35 P = 0.16 P = 0.49 No 1 1 1 1 Past chronic 1.84 (0.6–5.2) 1.11 (0.7–1.8) 1.17 (0.6–2.1) 1.33 (0.6–3.0) Active chronic 1.92 (0.5–6.9) 1.53 (0.7–3.2) 1.65 (0.7–3.8) 2.24 (0.7–7.3) Active 7.74 (1.8–32.7) 0.61 (0.2–2.1) 0.38 (0.1–1.9) 0.76 (0.1–7.1) 14 Bulletin of the World Health Organization | January 2007, 85 (1) Research Adverse birth outcomes in Tanzania Deborah Watson-Jones et al. Stillbirtha Prematurityb Low birth weightc Intrauterine growth retardationd Maternal anaemiaf P = 0.02 P = 0.11 P = 0.18 P = 0.93 No 1 1 1 1 Yes 3.74 (1.1–12.8) 1.40 (0.9–2.1) 1.42 (0.8–2.4) 1.03 (0.5–2.1) Note: bold type indicates a statistically significant result. a Adjusted for age, height, gravidity, history of stillbirth, HIV at delivery and maternal anaemia. Based on 1166 women with complete data for these variables. b Adjusted for age, occupation, gravidity, bacterial vaginosis during pregnancy, HIV at delivery and maternal malaria. Based on 1102 women with complete data for these variables. c Adjusted for age, tribe, occupation, height, gravidity, Chlamydia trachomatis at recruitment, HIV at delivery and maternal malaria. Based on 1090 women with complete data for these variables. d Adjusted for age, tribe, occupation, height, gravidity, baby’s sex, maternal malaria and HIV at delivery. Based on 964 women with complete data for these variables. e At recruitment or follow-up during pregnancy. f On admission for delivery. (Table 2, cont.) Population attributable fractions The proportions of adverse outcomes attributable to malaria, anaemia and HIV are shown in Table 3. The press ence of malaria in pregnancy, either maternal or placental, was associated with statistically significant PAFs of 34% for stillbirth, 20% for prematurity, 28% for LBW and 22% for IUGR. For prematurity, LBW and IUGR, the main associations were with peripheral maters nal malaria and active chronic placental malaria. In contrast, stillbirth appeared to be attributable to both peripheral and active or chronic placental malaria. A substantial proportion of stillbirths were attributable to maternal anaemia (PAF 63%). The proportion of adverse outcomes attributable to HIV was 5% or less for each outcome. Discussion There is a high incidence of adverse birth outcomes in northern United Republic of Tanzania, even in women who receive a package of reproductive health care as part of the antenatal services. Risk factors for adverse birth outcomes are multifactorial and only some of them are preventable or treatable. Documented risk factors for stills birth in subsSaharan Africa include low socioeconomic status, nulliparity, mas ternal syphilis, LBW, mode of delivery, a previous late fetal or early neonatal death and malaria, as well as anaemia and short stature as observed in this study.7,13, 27 However, in many African populations without access to screening, maternal syphilis will remain the most important preventable cause of stillbirth.7 Efforts to screen and treat for this infection must be a priority.28,29 Where syphilis screening and treatment is being implemented efs fectively, as in this study where adverse birth outcomes attributable to syphilis were effectively prevented, anaemia and placental malaria infection remain as other potentially preventable causes of stillbirth. The risk factors for LBW and IUGR in this study were similar to those described in a previous review which showed that ethnic group, nutrition, low weight prespregnancy, parity, young mas ternal age, short stature and malaria were important determinants of growth in utero in developing countries.14 In cons trast to research findings in Uganda,30 our study did not find any significant association on multivariate analysis between metronidazole treatment and LBW or preterm birth. Our study showed a strong assos ciation between preterm birth and the potentially preventable factors of BV and maternal malaria. Other determinants for prematurity in developing countries are unclear except for prespregnancy weight, maternal age and socioeconomic status. Vitamin A deficiency, which was not measured in our study, may also ins fluence premature births in subsSaharan Africa.17 The results of this study highs light several key points. First, as in other studies in subsSaharan Africa, there was a high prevalence of RTIs in pregnancy.31,32 However, apart from untreated BV, these had no significant association with adverse pregnancy outcome. Untreated RTIs have been ass sociated with all the adverse pregnancy outcomes documented in this study. Treating RTIs in pregnancy with a single dose of ceftriaxone in Nairobi has been shown to increase birth weight and reduce the incidence of postpartum ens dometritis.33 A study of mass treatment of RTIs in pregnant women in Uganda reported an increase in birth weight, and a reduction in rates of preterm birth and neonatal death in the intervention arm.32 In our study, in which treatment of RTIs was provided at several points in pregnancy, RTIs were not independent risk factors for adverse birth outcomes. This emphasizes the importance of inters vening against RTIs as a routine part of antenatal services because their impact on adverse outcomes can be prevented so effectively. This can be done through simple syndromic management at sevs eral points during antenatal care, but the use of rapid screening tests for RTIs, once available, may be more effective because they will identify asymptomatic infections. Resscreening women later in pregnancy and efforts to treat contacts should also be intensified. Second, in a population in which the impact of maternal syphilis in pregs nancy has been prevented, and in which most pregnant women have been treated for RTIs at the ANC, malaria and anaemia become the most significant preventable causes of adverse birth outs come. In this study, maternal malaria at delivery was a stronger independent risk factor for prematurity, LBW and IUGR than placental malaria, although active placental malaria infection was associated with stillbirth. In cases of maternal malaria, LBW can result from either IUGR or premature delivery.34,35 Infection acquired close to the time of delivery results in preterm birth, whereas antenatal infection acquired earlier ins creases the risk of IUGR.24 15Bulletin of the World Health Organization | January 2007, 85 (1) Research Adverse birth outcomes in Tanzania Deborah Watson-Jones et al. Table 3. Population attributable fractionsa for the association of maternal and placental malaria, anaemia and HIV infection with adverse pregnancy outcomes Adjusted prevalenceb Stillbirth Prematurity Low birth weight (LBW) Intrauterine growth retardation (IUGR) Any adverse outcomec Peripheral malaria 10.2% 13% (0–37%) 14% (6–22%) 25% (14–36%) 17% (5–28%) 15% (–22%) Placental malaria Past chronic 20.8% 10% (0–31%) 1% (0–11%) 2% (0–13%) 3% (0–10%) 3% (0–11%) Active chronic 11.4% 9% (0–30%) 10% (0–25%) 14% (0–38%) 13% (0–28%) 11% (2–23%) Active 3.8% 7% (0–18%) 0% (0–4%) 0% (0–2%) 0% (0–9%) 0% (0–5%) Any malariad 37.9% 34% (1–68%) 20% (5–35%) 28% (10–46%) 22% (7–36%) 22% (8–35%) Maternal anaemia 62.2% 63% (26–100%) 19% (0–45%) 22% (0–52%) 13% (0–34%) 23% (3–43%) Maternal HIV infection 10.5% 4% (0–21%) 0% (0–9%) 5% (0–13%) 4% (0–12%) 3% (0–9%) Note: bold type indicates a statistically significant result. a Calculated by bootstrapping the formula p(OR–1)/OR where p is the proportion of cases exposed in the target population, and the odds ratio (OR) is the adjusted OR in Table 3. Estimates are based on 1000 bootstrap samples. b Prevalence of exposure in the target population, adjusted for the weighted sample of rapid plasma reagin assay (RPR)-positive and negative women selected into the study. c Any pregnancy ending in a stillbirth or delivery of a preterm or a low-birth-weight infant or an infant with intrauterine growth retardation. d Evidence of placental and/or peripheral maternal malaria infection. In contrast to other studies in subs Saharan Africa, this study did not show any independent risk of adverse pregs nancy outcome associated with maternal HIV infection.36 However, an assos ciation between HIV status and both peripheral and placental malaria and higher parasite densities in HIVsinfected individuals was seen in this study as well as in several previous studies.37–39 Paritys specific immunity appears to be reduced in HIVspositive women; women of all parities have a higher relative risk for malaria if they are HIVspositive.27,37,39,40 This in turn may lead to an even higher rate of adverse pregnancy outcomes, als though we did not observe this, with the exception of a univariate effect of HIV on stillbirth. Any effect on pregnancy outcome may be partially mediated through the effect of HIV infection on malaria and/or anaemia. Malaria pros phylaxis may not be effective in this situation because placental parasitaemia was more common in HIVspositive than in HIVsnegative pregnant women treated with sulfadoxine–pyrimethamine in Kenya.38 Similar findings have been reported from Malawi.40 In developing countries, maternal anaemia is usually the result of iron deficiency and/or malaria. Hookworm infection and poor diet are believed to be important causes of iron deficiency.41,42 Iron supplementation during pregnancy is therefore generally recommended and has been shown to increase the haemos globin level and PCV in the mother’s blood postsdelivery and to increase the mean birth weight of infants.43 Maternal anaemia was not prevented in our study and this may relate to poor adherence to treatment with iron supplements or failure to control malaria adequately because of chloroquine resistance. Both malaria and HIV can affect pregnancy outcomes indirectly bes cause they are risk factors for maternal anaemia.2,42,44,45 Malaria prophylaxis in pregnancy can reduce the incidence of thirdstrimester anaemia 38 and is geners ally recommended as a part of prenatal care in malariasendemic areas.46 This has been effective in reducing the incidence of LBW infants, especially those born to primigravidae, and in reducing maternal anaemia.47–49 Trials of sulphadoxine– pyrimethamine have reduced placental malaria and may explain how chemos prophylaxis increases birth weight 38,50 Malaria prophylaxis has had little effect on the rate of other birth outcomes such as stillbirths or neonatal deaths.48 In our study, chloroquine was the recoms mended chemoprophylactic but had limited effectiveness in preventing infecs tion because chloroquine resistance is common.34 Efforts are now being made in many parts of subsSaharan Africa to change to more effective regimens.49 The potential impact of an effective intervens tion will be significant at the population level because more than one third of LBW and stillbirth cases and nearly a quarter of IUGR cases were attributs able to malaria. Given the relationship between malaria and HIV in pregnant women infected with both, it will be important to document the effectives ness of antiretroviral therapy for HIV on pregnancy outcomes and on the prevalence and severity of malaria in pregnancy in subsSaharan Africa as programmes of antiretroviral therapy are implemented. O Acknowledgements We thank the Ministry of Health, the National AIDS Control Programme and the Director General of the National Institute for Medical Research for pers mission to conduct and publish the study. We benefited enormously from the dedicated work of our fieldworkers in Makongoro Clinic, Bugando Medical Centre and Sengerema Designated Diss trict Hospital, United Republic of Tans zania, especially Leonard Ndeki, Mary Rusizoka, Zepherine Kanga and Janeth Marealle. We are grateful to Angela HuntsCooke, Julie Tucker, Tamara Hurst, Anne Buvé, Beryl West, Michel Alary, Danielle Fortin, Rosanna Peels ing, and the administrative staff of the National Institute for Medical Research 16 Bulletin of the World Health Organization | January 2007, 85 (1) Research Adverse birth outcomes in Tanzania Deborah Watson-Jones et al. (NIMR)/African Medical and Research Foundation (AMREF)/LSHTM cols laborative projects office. Throughout the study we received invaluable support and advice from many other colleagues at the National Institute for Medical Research, the African Medical and Res search Foundation, the London School of Hygiene and Tropical Medicine and elsewhere. The study was funded by the Wellcome Trust, London, England. We are very grateful to all the women who participated in this study. Competing interests: none declared. Résumé Issues défavorables de l’accouchement en Tanzanie - Influence et prévention des facteurs de risque maternels Objectif Déterminer les facteurs de risque pour diverses issues défavorables de l’accouchement et les fractions attribuables en population de ces issues. Méthodes 1688 femmes bénéficiant de soins anténataux ont été incluses dans une étude prospective visant à évaluer l’efficacité du dépistage de la syphilis et de son traitement. Pendant leur grossesse, ces femmes ont toutes été soumises à un dépistage de la syphilis et ont éventuellement été traitées contre cette maladie ou d’autres infections de l’appareil reproducteur. Elles ont également fait l’objet d’un suivi jusqu’à l’accouchement, en vue de mesurer l’incidence des mortinaissances, des retards de développement intra-utérins, des faibles poids à la naissance et des naissances avant terme. Résultats Parmi les 1536 accouchements, 2,7 % ont donné un enfant mort-né, 12 % un enfant prématuré vivant et 8 % un enfant de faible poids à la naissance. La mortinaissance était associée de manière indépendante aux facteurs suivants : antécédents d’accouchement d’un enfant mort-né, et faible stature ou anémie maternelles. Le faible poids à la naissance pouvait être associé à une petite stature de la mère, à son origine ethnique, à sa profession, au nombre de grossesses et à la présence du paludisme chez la mère, tandis que la naissance avant terme pouvait être mise en relation avec la profession, l’âge au début de l’activité sexuelle et la présence d’une vaginite bactérienne non traitée ou d’un paludisme chez la mère. Le retard de croissance intra-utérin pouvait être corrélé avec le nombre de grossesses, la présence d’un paludisme chez la mère, une faible stature maternelle et la mise au monde d’une fille. Parmi les femmes chez lesquelles on avait détecté et traité une syphilis, 20 à 24 % des issues défavorables de l’accouchement ont été considérées comme imputables au paludisme et 63 % des mortinaissances à une anémie maternelle. Le dépistage et le traitement des infections de l’appareil reproducteur se sont révélés efficaces et aucune association n’a été relevée entre ces infections et des issues défavorables de la grossesse. Conclusion Le paludisme et l’anémie maternels restent des causes importantes d’issues défavorables de la grossesse en Afrique subsaharienne. L’apport de services de santé génésique comprenant le traitement des infections de l’appareil reproducteur et la prévention du paludisme et de l’anémie chez la mère demeure une priorité pour réduire les issues défavorables de l’accouchement. Resumen Desenlaces adversos del parto en la República Unida de Tanzanía: impacto y prevención de los factores de riesgo maternos Objetivo Identificar los factores de riesgo de desenlace adverso del parto y sus fracciones poblacionales atribuibles. Métodos En un estudio prospectivo sobre la eficacia de la detección y tratamiento de la sífilis se incluyeron 1688 mujeres que esperaban recibir atención prenatal. Todas ellas fueron sometidas a pruebas de detección y tratamiento de la sífilis y de otras infecciones del aparato reproductor durante el embarazo, y fueron observadas hasta el parto para determinar la incidencia de muerte fetal, retraso del crecimiento intrauterino, bajo peso al nacer y parto antes del término. Resultados Entre las 1536 mujeres observadas hasta el parto hubo un 2,7% de muertes fetales, un 12% de nacidos vivos antes del término y un 8% de recién nacidos con bajo peso al nacer. La muerte fetal se asoció de forma independiente a los antecedentes de muerte fetal y a la anemia y la baja estatura de la madre. El bajo peso al nacer se asoció a la baja estatura de la madre, su etnia y ocupación, el número de embarazos anteriores y los antecedentes de paludismo, mientras que el parto antes del término se asoció con la ocupación, la edad de inicio de las relaciones sexuales, la vaginosis bacteriana no tratada y los antecedentes de paludismo. El retraso del crecimiento intrauterino se asoció con el número de embarazos anteriores, el paludismo, la baja estatura de la madre y el sexo femenino del recién nacido. En estas mujeres sometidas a pruebas de detección y tratamiento de la sífilis, entre un 20 y un 34% de cada uno de los desenlaces adversos fueron atribuibles al paludismo, mientras que el 63% de las muertes fetales fueron atribuibles a la anemia materna. La detección y tratamiento de las infecciones del aparato reproductor fue eficaz y no se observó ninguna asociación entre las infecciones tratadas y los desenlaces adversos del embarazo. Conclusión El paludismo y la anemia materna siguen siendo causas importantes de desenlace adverso del embarazo en el África subsahariana. La prestación de servicios de salud reproductiva que incluyan el tratamiento de las infecciones del aparato reproductor y la prevención de la malaria y la anemia materna siguen siendo prioritarias para reducir los desenlaces adversos del embarazo. 17Bulletin of the World Health Organization | January 2007, 85 (1) Research Adverse birth outcomes in Tanzania Deborah Watson-Jones et al. صخلم اهنم ةياقولاو ةيموملأا راطتخلاا لماوع رثأ :ةدحتلما اينازنت ةيروهمج في تادلاولل ةرئاضلا لئاصحلا اهئازجأو تادلاولل ةئيسلا لئاصحلل راطتخلاا لماوع لىع فرعتلا :فدهلا .ناكسلل ةوزعلما 1688 هتجلاعمو يرهزلا يرحت ةيلاعفل ةيقابتسا ةسارد تلمش :ةقيرطلا ءاسنلا عيمج يّرحت مت دقو ،ةدلاولل ةقباسلا ةياعرلا قفارم تراز ةضيرم للاخ ةيباجنلإا ةانقلل ىوادعلا نم هيرغبو يرهزلاب ةباصلإل نهتجلاعمو لخاد يننجلا توم( صلاملإا ثودح لدعم سايقل ةدلاولا ولتو لمحلا ةدلاوو ،ةدلاولا دنع ديلولا نزو صقنو ،محرلا لخاد ومنلا رخأتو ،)محرلا .)لمحلا ماتم لبق( جّدخلا ءايحلأا %12 نىاع مايف ،صلاملإا نم ًلاماح 1538 ينب نم %2.7 نىاع :تادوجولما صلاملإا قفارت دقو .ةدلاولا دنع ديلولا نزو صقن نم %8و جادخلا نم نهنم نزو صقن قفارت مايف ،مدلا رقفو تاهملأا ةماق صرقو صلاملإل قباوس عم ةنهلماو )ام قرعل ءماتنلاا( ةينثلإابو تاهملأا ةماق صرقب ةدلاولا دنع ديلولا رمعلاو ةنهلما عم جادِخلا قفارتو ،تاهملأا ىدل ايرلالماو لومحلا ددعتو ايرلالماو ةََجلاعلما يرغ لبهلما ضارمأو ،ةيسنجلا ةقلاعلل ةسرمام لوأ دنع ىدل ايرلالماو لومحلا ددعتب محرلا لخاد ومنلا رخأت قفارتو .تاهملأا ىدل مت تياوللا ءاسنلا ينب نمو .ىثنلأل نهتدلاوو نهيدل ةماقلا صرقو تاهملأا نم %34 لىإ %20 نم نأ ردق يرهزلاب نهتباصلإ نهتجلاعمو نهحسم لىإ نْيَزعُي دق نهنأ ر َّدقي لئاصحلا عيمج نم ةدحاو نهيدل تيلالا ءاسنلا دقو .ايرلالما نع مجانلا مدلا رقف لىإ ىزعي صلاملإا نم %63 نأو ،ايرلالما ىوادعلا ينب قفارت ظحلاي لمو ،ًلااعف ةيباجنلإا ةانقلل ىوادعلا يرحت ناك .لمحلل ةرئاضلا لئاصحلا ينبو ةيباجنلإا ةانقلا في ةيباهتللاا لئاصحلل ةماهلا تاببسلما نم تاهملأا ينب مدلا رقفو ايرلالما لازتلا :جاتنتسلاا يعدتسيو .ةيقيرفلأا ءارحصلا بونج في ةعقاولا نادلبلا في لمحلل ةرئاضلا ليبسلا ىودع ةجلاعم لمشت يتلاو ،ةيباجنلإا ةحصلا تامدخ ميدقت رملأا نم دحلا فدهب ،تاهملأا ىدل مدلا رقفو ايرلالما نم ةياقولاو بياجنلإا .تايولولأا نم كلذ لك رابتعاو ،ةرئاضلا ةيدلاولا لئاصحلا References 1. McCormick MC. The contribution of low birth weight to infant mortality and childhood mortality. N Engl J Med 1985;31:82-90. 2. Brabin BJ. An analysis of malaria in pregnancy in Africa. Bull World Health Organ 1983;61:1005-16. 3. McGregor IA. Epidemiology, malaria and pregnancy. Am J Trop Med Hyg 1984;77:517-25. 4. Temmerman M, Plummer FA, Mirza NB, Ndinya-Achola JO, Wamola IA, Nagelkerke N, et al. Infection with HIV as a risk factor for adverse obstetrical outcome. AIDS 1990;4:1087-93. 5. Leroy V, Ladner J, Nyiraziraje M, De Clercq A, Bazubagira A, Van de Perre P, et al. Effect of HIV-1 infection on pregnancy outcome in women in Kigali, Rwanda, 1992-1994. AIDS 1998;12:643-50. 6. McDermott J, Steketee R, Larsen S, Wirima J. Syphilis-associated perinatal and infant mortality in rural Malawi. Bull World Health Organ 1993;71:773-80. 7. Watson-Jones D, Changalucha J, Gumodoka B, Weiss H, Rusizoka M, Ndeki L, et al. Syphilis and pregnancy outcomes in Tanzania I. Impact of maternal syphilis on outcome of pregnancy in Mwanza Region, Tanzania. J Infect Dis 2002;186:940-7. 8. Hillier SL, Nugent RP, Eschenbach DA, Krohn MA, Gibbs RS, Martin DH, et al. Association between bacterial vaginosis and preterm delivery of a low-birth- weight infant. N Engl J Med 1995;333:1737-42. 9. Donders GGG, Desmyter J, De Wet DH, Van Assche FA. The association of gonorrhoea and syphilis with premature birth and low birthweight. Genitourin Med 1993;69:98-101. 10. Martius J, Krohn MA, Hillier SL, Stamm WE, Holmes KK, Eschenbach DA. Relationships of vaginal Lactobacillus species, cervical Chlamydia trachomatis, and bacterial vaginosis to preterm birth. Obstet Gynecol 1988;71:89-95. 11. Gravett MG, Nelson HP, DeRouen T, Critchlow C, Eschenbach DA, Holmes KK. Independent associations of bacterial vaginosis and Chlamydia trachomatis infection with adverse pregnancy outcome. JAMA 1986;256:1899-903. 12. Cotch MF, Pastorek JG, Nugent RP, Hillier SL, Gibbs RS, Martin DH, et al. Trichomonas vaginalis associated with low birth weight and preterm delivery. Sex Transm Dis 1997;24:353-60. 13. McDermott JM, Wirima JJ, Steketee RW, Breman JG, Heymann DL. The effect of placental malaria infection on perinatal mortality in rural Malawi. Am J Trop Med Hyg 1996;55:61-5. 14. Kramer MS. Determinants of low birth weight: methodological assessment and meta-analysis. Bull World Health Organ 1987;65:663-737. 15. Prentice AM, Cole TJ, Whitehead RG. Food supplementation in pregnant women. Eur J Clin Nutr 1988;42:87-9. 16. Villar J, Gulmezoglu AM, de Onis M. Nutritional and antimicrobial interventions to prevent preterm birth: an overview of randomised controlled trials. Obstet Gynecol Surv 1998;53:575-85. 17. Coutsoudis A, Pillay K, Spooner E, Kuhn L, Coovadia HM. Randomised trial testing the effect of vitamin A supplementation on pregnancy outcomes and early mother-to-child HIV-1 transmission in Durban, South Africa. AIDS 1999;13:1517-24. 18. Fleming AF. Tropical obstetrics and gynaecology. I. Anaemia in pregnancy in tropical Africa. Trans R Soc Trop Med Hyg 1989;83:441-8. 19. Sullivan AD, Nyirenda T, Cullinan T, Taylor T, Harlow SD, James SA, et al. Malaria infection during pregnancy: intrauterine growth retardation and preterm delivery in Malawi. J Infect Dis 1999;179:1580-3. 20. Jana N, Vasishta K, Jindal SK, Khunnu B, Ghosh K. Perinatal outcome in pregnancies complicated by pulmonary tuberculosis. Int J Gynaecol Obstet 1994;44:119-24. 21. Watson-Jones D, Gumodoka B, Weiss H, Changalucha J, Todd J, Mugeye K, et al. Syphilis in pregnancy in Tanzania II. The effectiveness of antenatal syphilis screening and single dose benzathine penicillin treatment for the prevention of adverse pregnancy outcomes. J Infect Dis 2002;186:948-57. 22. World Health Organization. International classification of diseases and health related problems. Tenth Revision. Geneva: World Health Organization; 1992. 23. Walsh JA, Feifer CM, Measham AR, Gertler PJ. Maternal and perinatal health. In: Jamison DT, Mosley WH, Measham AR, Bobadilla JL, editors. Disease control priorities in developing countries. 1st ed. New York: Oxford University Press; 1993. p. 363-89. 24. Nugent RP, Krohn MA, Hillier SL. Reliability of diagnosing bacterial vaginosis is improved by a standardized method of Gram stain interpretation. J Clin Microbiol 1991;29:297-301. 25. Bulmer JN, Rasheed FN, Francis N, Morrison L, Greenwood BM. Placental malaria. I. Pathological classification. Histopathology 1993;22:211-8. 26. Benichou J, Gail MH. Estimates of absolute cause-specific risk in cohort studies. Biometrics 1990;46:813-26. 27. Ticconi C, Mapfumo M, Dorrucci M, Naha N, Tarira E, Pietropolli A, et al. Effect of maternal HIV and malaria infection on pregnancy and perinatal outcome in Zimbabwe. J Acquir Immune Defic Syndr 2005;34:289-94. 28. Peeling RW, Mabey D, Fitzgerald DW, Watson-Jones D. Avoiding HIV and dying of syphilis. Lancet 2005;364:1561-3. 29. Gloyd S, Chai S, Mercer MA. Antenatal syphilis in sub-Saharan Africa: missed opportunities for mortality reduction. Health Policy Plan 2001;16:29-34. 30. Kigozi GG, Brahmbhatt H, Wabwire-Mangen F, Wawer M, Serwadda D, Sewankambo N, et al. Treatment of Trichomonas in pregnancy and adverse outcomes of pregnancy: a subanalysis of a randomized trial in Rakai, Uganda. Am J Obstet Gynecol 2005;189:1398-401. 31. Blankhart D, Muller O, Gresenguet G, Weis P. Sexually transmitted infections in young pregnant women in Bangui, Central African Republic. Int J STD AIDS 1999;10:609-14. 18 Bulletin of the World Health Organization | January 2007, 85 (1) Research Adverse birth outcomes in Tanzania Deborah Watson-Jones et al. 32. Gray RH, Wabwire-Mangen F, Kigozi G, Sewankambo N, Serwadda D, Moulton LH, et al. Randomized trial of presumptive sexually transmitted disease therapy during pregnancy in Rakai, Uganda. Am J Obstet Gynecol 2001;185:1209-17. 33. Temmerman M, Njagi E, Nagelkerke N, Ndinya-Achola J, Plummer FA, Meheus A. Mass antimicrobial treatment in pregnancy: a randomized placebo-controlled trial in a population with high rates of sexually transmitted diseases. J Reprod Med 1995;40:176-80. 34. Steketee RW, Wirima JJ, Hightower AW, Slutsker L, Heymann DL, Breman JG. The effect of malaria and malaria prevention in pregnancy on offspring birthweight, prematurity, and intrauterine growth retardation in rural Malawi. Am J Trop Med Hyg 1996;55:33-41. 35. Matteelli A, Caligaris S, Castelli F, Carosi G. The placenta and malaria. Ann Trop Med Parasitol 1997;91:803-10. 36. Ayisi JG, van Eijk AM, ter Kuile FO, Kolzac MS, Otieno JA, Misore AO, et al. The effect of dual infection with HIV and malaria on pregnancy outcome in western Kenya. AIDS 2003;17:585-94. 37. van Eijk AM, Ayisi JG, ter Kuilee FO, Misore AO, Otieno JA, Rosen D, et al. HIV increases the risk of malaria in women of all gravidities in Kisumu, Kenya. AIDS 2003;17:595-603. 38. Parise ME, Ayisi JG, Nahlen BL, Schultz LJ, Roberts JM, Misore A, et al. Efficacy of sulfadoxine-pyrimethamine for prevention of placental malaria in an area of Kenya with a high prevalence of malaria and human immunodeficiency virus infection. Am J Trop Med Hyg 1998;59:813-22. 39. Steketee RW, Wirima JJ, Bloland PB, Chilima B, Mermin JH, Chitsulo L, et al. Impairment of pregnant woman’s acquired ability to limit Plasmodium falciparum by infection with human immunodeficiency virus type-1. Am J Trop Med Hyg 1996;55:42-9. 40. Verhoeff FH, Brabin BJ, Hart CA, Chimsuku L, Kazembe P, Broadhead RL. Increased prevalence of malaria in HIV-infected pregnant women and its implications for malaria control. Trop Med Int Health 1999;4:5-12. 41. Massawe SN, Urassa ENJ, Mmari M, Ronquist G, Lindmark G, Nystrom L. The complexity of pregnancy anaemia in Dar es Salaam. Gynecol Obstet Invest 1999;47:76-82. 42. Shulman CE, Graham WJ, Jilo H. Malaria is an important cause of anaemia in primigravidae: evidence from a district hospital in coastal Kenya. Trans R Soc Trop Med Hyg 1996;90:535-9. 43. Menendez C, Todd J, Alonso PL, Francis N, Lulat S, Ceesay S, et al. The effects of iron supplementation during pregnancy, given by traditional birth attendants, on the prevalence of anaemia and malaria. Trans R Soc Trop Med Hyg 1994;88:590-3. 44. Zucker JR, Lackritz EM, Ruebush TK, Hightower AW, Adungosi JE, Were JBO, et al. Anaemia, blood transfusion practices, HIV and mortality among women of reproductive age in western Kenya. Trans R Soc Trop Med Hyg 1994; 88:173-6. 45. Nosten F, ter Kuile F, Maelankirri L, Decludt B, White NJ. Malaria during pregnancy in an area of unstable endemicity. Trans R Soc Trop Med Hyg 1991; 85:424-9. 46. World Health Organization. WHO Expert Committee on Malaria. 18th Report. Geneva: World Health Organization; 1986, p. 735. 47. Greenwood AM, Menendez C, Todd J, Greenwood BM. The distribution of birth weights in Gambian women who received malaria chemoprophylaxis during their first pregnancy and control women. Trans R Soc Trop Med Hyg 1994;88:311-2. 48. Greenwood BM, Greenwood AM, Snow RW, Byass P, Bennett S. Hatib-N’jie AB. The effects of malaria chemoprophylaxis given by traditional birth attendants on the course and outcome of pregnancy. Trans R Soc Trop Med Hyg 1989;83:589-93. 49. Shulman CE, Dorman EK, Cutts F, Kawuondo K, Bulmer JN, Peshu N, et al. Intermittent sulphadoxine-pyrimethamine to prevent severe anaemia secondary to malaria in pregnancy: a randomised placebo-controlled trial. Lancet 1999;353:632-6. 50. Verhoeff FH, Brabin BJ, Chimsuku L, Kazembe P, Russell WB, Broadhead WB. An evaluation of the effects of intermittent sulfadoxine-pyrimethamine treatment in pregnancy on parasite clearance and risk of low birthweight in rural Malawi. Ann Trop Med Parasitol 1998;92:141-50.