Antenatal Clinic Data Research Articles

Impact of ART on the fertility of HIV-positive women in sub-Saharan Africa.

Understanding the fertility of HIV-positive women is critical to estimating HIV epidemic trends from surveillance data and to planning resource needs and coverage of prevention of mother-to-child transmission services in sub-Saharan Africa. In the light of the considerable scale-up in antiretroviral therapy (ART) coverage over the last decade, we conducted a systematic review of the impact of ART on the fertility outcomes of HIV-positive women. We searched Medline, Embase, Popline, PubMed and African Index Medicus. Studies were included if they were conducted in sub-Saharan Africa and provided estimates of fertility outcomes (live births or pregnancies) among women on ART relative to a comparison group. Of 2070 unique references, 18 published papers met all eligibility criteria. Comparisons fell into four categories: fertility of HIV-positive women relative to HIV-negative women; fertility of HIV-positive women on ART compared to those not yet on ART; fertility differences by duration on ART; and temporal trends in fertility among HIV-positive women. Evidence indicates that fertility increases after approximately the first year on ART and that while the fertility deficit of HIV-positive women is shrinking, their fertility remains below that of HIV-negative women. These findings, however, were based on limited data mostly during the period 2005-2010 when ART scaled up. Existing data are insufficient to characterise how ART has affected the fertility of HIV-positive women in sub-Saharan Africa. Improving evidence about fertility among women on ART is an urgent priority for planning HIV resource needs and understanding HIV epidemic trends. Alternative data sources such as antenatal clinic data, general population cohorts and population-based surveys can be harnessed to understand the issue.

Reply to SA Tanumihardjo et al.

Reply to SA Tanumihardjo et al.

Do HIV prevalence trends in antenatal clinic surveillance represent trends in the general population in the antiretroviral therapy era? The case of Manicaland, East Zimbabwe.

National estimates of HIV trends in generalized epidemics rely on HIV prevalence data from antenatal clinic (ANC) surveillance. We investigate whether HIV prevalence trends in ANC data reflect trends in men and women in the general population during the scale-up of antiretroviral therapy (ART) in Manicaland, Zimbabwe. Trends in HIV prevalence in local ANC attendees and adults aged 15-49 years in towns, agricultural estates, and villages were compared using five rounds of parallel ANC (N = 1200) and general-population surveys (N = 10 000) and multivariable log-linear regression. Changes in the age pattern of HIV prevalence and the age distribution of ANC attendees were compared with those in the general population. Age-specific pregnancy prevalence rates were compared by HIV infection and ART status. Cumulatively, from 1998-2000 to 2009-2011, HIV prevalence fell by 60.0% (95% confidence interval, 51.1-67.3%) in ANC surveillance data and by 34.3% (30.8-37.7%) in the general population. Most of the difference arose following the introduction of ART (2006-2011). The estates and villages reflected this overall pattern but HIV prevalence in the towns was lower at local ANCs than in the general population, largely because of attendance by pregnant women from outlying (lower prevalence) areas. The ageing of people living with HIV in the general population (52.4% aged >35 years, 2009-2011) was under-represented in the ANC data (12.6%) because of lower fertility in older and HIV-infected women. After the introduction of ART in Manicaland, HIV prevalence declined more steeply in ANC surveillance data than in the general population. Models used for HIV estimates must reflect this change in bias.

Potential Cost-Effectiveness of Schistosomiasis Treatment for Reducing HIV Transmission in Africa – The Case of Zimbabwean Women

BackgroundEpidemiological data from Zimbabwe suggests that genital infection with Schistosoma haematobium may increase the risk of HIV infection in young women. Therefore, the treatment of Schistosoma haematobium with praziquantel could be a potential strategy for reducing HIV infection. Here we assess the potential cost-effectiveness of praziquantel as a novel intervention strategy against HIV infection.MethodsWe developed a mathematical model of female genital schistosomiasis (FGS) and HIV infections in Zimbabwe that we fitted to cross-sectional data of FGS and HIV prevalence of 1999. We validated our epidemic projections using antenatal clinic data on HIV prevalence. We simulated annual praziquantel administration to school-age children. We then used these model predictions to perform a cost-effectiveness analysis of annual administration of praziquantel as a potential measure to reduce the burden of HIV in sub-Saharan Africa.FindingsWe showed that for a variation of efficacy between 30–70% of mass praziquantel administration for reducing the enhanced risk of HIV transmission per sexual act due to FGS, annual administration of praziquantel to school-age children in Zimbabwe could result in net savings of US$16–101 million compared with no mass treatment of schistosomiasis over a ten-year period. For a variation in efficacy between 30–70% of mass praziquantel administration for reducing the acquisition of FGS, annual administration of praziquantel to school-age children could result in net savings of US$36−92 million over a ten-year period.ConclusionsIn addition to reducing schistosomiasis burden, mass praziquantel administration may be a highly cost-effective way of reducing HIV infections in sub-Saharan Africa. Program costs per case of HIV averted are similar to, and under some conditions much better than, other interventions that are currently implemented in Africa to reduce HIV transmission. As a cost-saving strategy, mass praziquantel administration should be prioritized over other less cost-effective public health interventions.

A new infectious disease model for estimating and projecting HIV/AIDS epidemics

ObjectivesAs the global HIV pandemic enters its fourth decade, countries have collected longer time series of surveillance data, and the AIDS-specific mortality has been substantially reduced by the increasing availability...

Use of service data to inform pediatric HIV-free survival following prevention of mother-to-child transmission programs in rural Malawi

BackgroundRecent years have seen rapid and significant progress in science and implementation of programs to prevent mother-to-child transmission of HIV. Programs that support PMTCT routinely monitor service provision but very few have measured their effectiveness. The objective of the study was to use service data to inform HIV-free survival among HIV exposed children that received antiretroviral drugs to prevent mother-to-child transmission (PMTCT) of HIV. The study was conducted in two rural districts in Malawi with support from FHI 360.MethodsA descriptive observational study of PMTCT outcomes was conducted between June 2005 and June 2009. The dataset included patient-level data of all pregnant women 1) that tested HIV-positive, 2) that were dispensed with antiretroviral prophylaxis, and 3) whose addresses were available for home visits. The data were matched to each woman’s corresponding antenatal clinic data from home visit registers.ResultsOut of 438 children whose home addresses were available, 33 (8%) were lost to follow-up, 35 (8%) were alive but not tested for HIV by the time home visit was conducted, and 52 (12%) were confirmed deceased. A total of 318 children were alive at the time of the home visit and had an HIV antibody test done at median age 15 months. The resulting estimated 24-month probability of HIV-free survival over all children was 78%. Among children who did not receive nevirapine, the estimated 24-month probability of HIV-free survival was 61%, and among those who did receive NVP syrup the estimate was 82%.ConclusionsWhen mothers and newborns received nevirapine, the estimated 24-month probability of HIV-free survival among children was high at 82% (CI: 54% to 99%). However this conclusion should be interpreted cautiously 1) due to the wide confidence interval; and 2) because the confidence interval range includes 55%, which is the natural HIV-free survival rate in the absence of a PMTCT intervention. This analysis highlighted the need of quality data and well-structured home visits to assess PMTCT effectiveness.

Declining Syphilis Trends in Concurrence With HIV Declines Among Pregnant Women in Zambia

Zambia has a serious HIV epidemic and syphilis infection remains prevalent in the adult population. We investigated syphilis trends using national antenatal clinic (ANC) sentinel surveillance data in Zambia and compared the findings with population-based data. The analyses are based on ANC data from 22 sentinel sites from five survey rounds conducted between 1994 and 2008. The data comprised information from interviews and syphilis and HIV test results. The syphilis estimates for 2002 and 2008 were compared with data from the Demographic and Health Surveys 2001/2002 and 2007, which are nationally representative data, and also included syphilis testing and HIV. The overall syphilis prevalence dropped during the period 1994-2008 among both urban and rural women aged 15 to 49 years (9.8% to 2.8% and 7.5% to 3.2%, respectively). However, provincial variations were striking. The decline was steep irrespective of educational level, but among those with the highest level the decline started earlier and was steeper than among those with low education. The comparison with Zambia Demographic and Health Surveys 2001/2002 and 2007 findings also showed an overall reduction in syphilis prevalence among urban and rural men and women in the general population. The syphilis prevalence declined by 65% in urban and 59% in rural women. Provincial variations need to be further studied to better guide specific sexually transmitted infection prevention and control programmes in different geographical settings. The national ANC-based HIV and syphilis surveillance system provided good proxies of syphilis prevalence and trends.

P1-S1.46 Syphilis trends in Zambia - a 14-year observation

BackgroundSyphilis and other STIs are prevalent in sub-Saharan Africa, perhaps due to lack of effective curative services. Estimates among pregnant women and in the general population in Zambia range from 6% to 18%, with maternal syphilis contributing to a high number of mid-trimester abortions, still births, prematurity, and morbidity and mortality of the child. Existing evidence suggests that control of syphilis and other ulcerative and non-ulcerative STIs remains one of the key strategies for HIV control. There are no recent studies from Zambia comparing syphilis prevalence with HIV trends.ObjectivesTo investigate trends in syphilis prevalence using Antenatal Clinic (ANC) sentinel surveillance data, and to validate the findings with population-based data.MethodsThe analyses are based on ANC data from 1994 to 2008 from 22 sites. Estimates are compared with data from Zambia Demographic and Health Surveys (ZDHS) 2001/2002 and 2007. Analyses were restricted to women aged 15–49 years and 15–24 years. ORs with 95% CIs were used to test whether the prevalence trends were significant.ResultsThe overall syphilis prevalence dropped during the period 1994–2008 among both urban and rural women aged 15–49 years from 9.8% to 2.8% and 7.5% to 3.2%, respectively. Provincial variation was observed with a tendency towards a reduction. A sharper decline in syphilis prevalence was observed among women with more years in school than among those with fewer schooling years. A declining trend was also seen among young primi gravid women aged 15–19 years. A comparison of ZDHS 2001/2002 and 2007 findings also showed an overall reduction in syphilis prevalence in the general population.ConclusionsThere was an overall reduction in syphilis prevalence and this decline was sharper than the decline in HIV during the same period. In part this could be attributed to the revamping of STI services in the country. Reduction in both HIV and syphilis prevalence could also suggest a reduction in the disease incidence and is likely to partially reflect positive sexual behaviour changes. Provincial variations were striking and need to be further studied to better guide specific STI prevention and control programmes in different geographical settings.

Comparison of HIV Prevalence Estimates From Sentinel Surveillance and a National Population-Based Survey in Uganda, 2004-2005

HIV programs in generalized epidemics have traditionally relied on antenatal clinic (ANC) sentinel surveillance data to guide prevention and to model epidemic trends. ANC data, however, come from a subset of the population, and their representativeness of the population has been debated. Data from a national population-based Uganda HIV/AIDS Sero-Behavioral Survey (UHSBS) were compared with those from ANC sentinel surveillance. Using geographic information system, UHSBS clusters within a 30 km radius of the ANC sites were mapped. Estimates of HIV prevalence from ANC surveillance were compared with those from UHSBS. The ANC-based HIV prevalence, 6.0% [confidence interval (CI) 5.5% to 6.5%], was similar to that from UHSBS, 5.9% (CI 5.4% to 6.4%). The ANC-based estimate correlated with that of UHSBS catchment area women who were pregnant and those who had given birth in the 2 years preceding the survey. ANC data overestimated prevalence in the 15-year to 19-year age group, were similar to UHSBS for ages 20-29 years, and underestimated prevalence in older respondents. ANC data underestimated HIV prevalence among women (6.0% vs. 7.4%; CI 6.6% to 8.2%) and urban women (7.6% vs. 12.7%) but was similar for rural women (5.3% vs. 4.9%). ANC-based surveillance remains an important tool for monitoring HIV/AIDS programs. ANC and UHSBS data were similar overall and for 15-year to 29-year olds, women who were pregnant, and women who had a birth in the 2 years before the survey. ANC estimates were lower in those > or = 30 years and in urban areas. Periodic serosurveys to adjust ANC-based estimates are needed.

Long-term population effect of male circumcision in generalised HIV epidemics in sub-Saharan Africa

This paper examines the complex relationship between male circumcision and HIV prevalence and incidence in sub-Saharan African countries that have generalised epidemics. In South Africa, the mean yearly HIV incidence and an estimate of the net reproduction rate of the epidemic (R 0) (in this case, the ratio of the number of HIV-infected persons between 1994 and 2004 to the number of persons infected in 1994 from which they were presumed to have become infected) were computed from antenatal clinic data for the period 1994–2004, and then compared, by province, to prevailing levels of male circumcision (high, medium and low). In South Africa, mean yearly HIV incidence and net reproduction rate of the epidemic were not lower in provinces with higher levels of male circumcision. For thirteen other countries where Demographic and Health Survey data were available, male HIV prevalence in circumcised and non-circumcised groups was compared. A meta-analysis of that data, contrasting male HIV seroprevalence according to circumcision status, showed no difference between the two groups (combined risk ratio [RR] = 0.99, 95% CI = 0.94–1.05). Individual case study analysis of eight of those countries showed no significant difference in seroprevalence in circumcised and uncircumcised groups, while two countries (Kenya and Uganda) showed lower HIV prevalence among circumcised groups, and three countries (Cameroon, Lesotho and Malawi) showed higher HIV prevalence among circumcised groups. In most countries with a complex ethnic fabric, the relationship between men's circumcision status and HIV seroprevalence was not straightforward, with the exception of the Luo in Kenya and a few groups in Uganda. These observations put into question the potential long-term effect of voluntary circumcision programmes in countries with generalised HIV epidemics.

Estimating and projecting HIV prevalence and AIDS deaths in Tanzania using antenatal surveillance data

BackgroundThe Estimations and Projections Package (EPP 2005) for HIV/AIDS estimates and projects HIV prevalence, number of people living with HIV and new HIV infections and AIDS cases using antenatal clinic (ANC) surveillance data. The prevalence projection produced by EPP can be transferred to SPECTRUM, a demographic projectionmodel, to calculate the number of AIDS deaths. This paper presents estimates and projections of HIV prevalence, new cases of HIV infections and AIDS deaths in Tanzania between 2001 and 2010 using the EPP 2005 and SPECTRUM soft-wares on ANC data.MethodsFor this study we used; the 1985 – 2004 ANC data set, the 2005 UN population estimates for urban and rural adults, which is based on the 2002 population census, and results of the 2003 Tanzania HIV Indicator Survey. The ANC surveillance sites were categorized into urban and rural areas on the basis of the standard national definitions of urban and rural areas, which led to 40 urban and 35 rural clinic sites. The rural and urban epidemics were run independently by fitting the model to all data and on level fits.ResultsThe national HIV prevalence increased from 0% in 1981 to a peak of 8.1% in 1995, and gradually decreased to 6.5% in 2004 which stabilized until 2010. The urban HIV epidemic increased from 0% in 1981 peaking at 12.6% in 1992 and leveled to between 10.9% and 11.8% from 2003 to 2010. The rural epidemic peaked in 1995 at 7.0% and gradually declined to 5.2% in 2004, and then stabilized at between 5.1% and 5.3% from 2005 to 2010. New infections are projected to rise steadily, resulting in 250,000 new cases in 2010. Deaths due to AIDS started in 1985 and rose steadily to reach 120,000 deaths in 2010, with more females dying than men.ConclusionThe fact that the number of new infections is projected to increase steadily to reach 250,000 per year in 2010 calls for more concerted efforts to combat the spread of HIV infection particularly in the rural areas where the infrastructure needed for prevention programmes such as counseling and testing, condom accessibility and AIDS information is less developed.

Differences in fertility by HIV serostatus and adjusted HIV prevalence data from an antenatal clinic in northern Uganda

To estimate differences in fertility by HIV serostatus and to validate an adjustment method for estimating the HIV prevalence in the general female population using data from an antenatal clinic. We used Cox regression models to retrospectively estimate the age-specific relative fertility (RF) of HIV-positive compared to HIV-negative women among 3314 antenatal clinic attenders in northern Uganda. RF and the age distribution of women in the general female population were used to extrapolate the antenatal clinic-based HIV prevalence. This procedure was indirectly validated by comparing the adjusted estimate with those based on standard adjustment factors derived from general female populations in Uganda and Tanzania. HIV-positive women reported a lower fertility than HIV-negative women [age-adjusted RF=0.83, 95% confidence interval (CI): 0.75-0.93]. Except for girls aged 15-19 (RF=0.96, 95% CI: 0.74-1.24) HIV-positive women in all age groups were less fertile (20-24 year: RF=0.83, 95% CI: 0.67-1.01; 25-29 years: RF=0.79, 95% CI: 0.62-1.00; 30-49 year: RF=0.79, 95% CI: 0.65-0.96]. Adjusting the antenatal clinic-based HIV prevalence (11.6%) for these differences yields a higher estimate (13.8%) that is lower than those based on standard adjustment factors derived from general female populations (from 14.6% to 17.7%). The age-specific pattern of differential fertility by HIV serostatus derived from antenatal clinic data is consistent with findings from population-based studies conducted in Africa. However, differences in fertility between HIV positive and HIV-negative clients underestimate those in the general female population yielding inaccurate estimates when used to extrapolate the HIV prevalence.

Nationwide HIV prevalence survey in general population in Niger

A national population-based survey was carried out in Niger in 2002 to assess HIV prevalence in the population aged 15-49 years. A two-stage cluster sampling was used and the blood specimens were collected on filter paper and tested according to an algorithm involving up to three diagnostic tests whenever appropriate. Testing was unlinked and anonymous. The refusal rate was 1.1% and 6056 blood samples were available for analysis. The adjusted prevalence of HIV was 0.87% (95% CI, 0.5-1.3%) and the 95% CI of the estimated number of infected individuals was 22 864-59 640. HIV-1 and HIV-2 represented, respectively, 95.6% and 2.9% of infections while dual infections represented 1.5%. HIV positivity rate was 1.0% in women and 0.7% in men. It was significantly higher among urban populations than among rural ones (respectively, 2.1% and 0.6%, P < 10(-6)). Using logistic regression, the variables significantly related to the risk of being tested positive for HIV were urban housing, increasing age and being either widowed or divorced. The estimate from the national survey was lower than the prevalence assessed from antenatal clinic data (2.8% in 2001). In the future, the representativeness of sentinel sites should be improved by increasing the representation of rural areas accounting for more than 80% of the population. Compared with other sub-Saharan countries, the HIV prevalence in Niger is still moderate. This situation represents a strong argument for enhancing prevention programmes and makes realistic the projects promoting an access to potent antiretroviral therapies for the majority.

How well do antenatal clinic (ANC) attendees represent the general population? A comparison of HIV prevalence from ANC sentinel surveillance sites with a population-based survey of women aged 15-49 in Cambodia

The purpose of this study was to evaluate whether HIV-1 prevalence among antenatal clinic (ANC) attendees in Cambodia provided a reasonable estimate of HIV-1 prevalence among all women 15-49 years. METHODS Antenatal clinic attendees in five HIV sentinel surveillance sites (five provinces) were selected by consecutive sampling (n = 1695). The population survey of females by household was carried out in the same five areas. Household females aged 15-49 years were selected using a three-stage cluster sampling design (n = 3066). Serum-based HIV ELISA testing was done for both ANC attendees and household females. The HIV prevalence for ANC attendees and household females were compared by age group and urban versus rural location. The overall prevalence of HIV-1 infection among ANC attendees (1.62%, 95% CI : 1.26-1.98) was similar to the overall prevalence obtained from the general population of household females (1.24%, 95% CI : 0.92-1.55) in the same catchment areas in Cambodia. In the rural areas, the overall HIV prevalence among ANC attendees (2.18%, 95% CI : 1.59-2.77) was significantly higher than among the household females (0.86%, 95% CI : 0.49-1.23) after adjustment for age distribution and education level. In the 15-24 age group in rural areas, the HIV prevalence of ANC women was 2.71% (95% CI : 0.96-4.46) compared with 0.77% (95% CI : 0.02-1.53) in household females. Although ANC data can be used to estimate trends over time, it should be realized that ANC data may overestimate the actual prevalence in the younger age group in rural areas in Cambodia.

Trend in HIV-1 prevalence in an antenatal clinic in North Uganda and adjusted rates for the general female population.

To estimate HIV-1 prevalence among women attending an antenatal clinic in the Gulu District (North Uganda) and, based on these data, among the district's female population. Anonymous HIV-1 screening was performed for 8555 antenatal clinic attendees aged 15-39 years in the period 1993-1997. The results were used to estimate the prevalence among the district's female population, accounting for differences in fertility rates by HIV-1 serostatus. Among antenatal clinic attendees, HIV-1 prevalence showed a significant linear decrease (P < 0.001), from 26.0% in 1993 [95% confidence Interval (CI), 23.2-29.0%] to 16.1% in 1997 (95% CI, 14.8-17.5%). This decrease was mostly due to a marked decrease until 1995 (14.3%; 95% Cl, 12.7-16.0%) and was more pronounced among women aged under 30 years (P < 0.001), from both urban and rural areas (P < 0.001). The risk of being infected was higher among women from urban areas (Gulu Municipality), both over the entire period (adjusted prevalence proportion ratio = 1.54; 95% CI, 1.40-1.68) and by individual year. The estimated prevalence for the 15-39-year-old female population, standardized by age and area of residence, decreased from 25.4% in 1993-1994 to 17.8% in 1996-1997; these rates were 1.22 and 1.28 times higher, respectively, than those among antenatal clinic attendees. The trend of decrease among young women, for whom changes in HIV-1 prevalence more closely reflect incidence, could be partially due to a reduction in risk behaviour and a consequent decreasing incidence. Differences in fertility rates by HIV-1 serostatus should be addressed when using antenatal clinic data to estimate prevalence among the general female population.

Adjusting ante-natal clinic data for improved estimates of HIV prevalence among women in sub-Saharan Africa.

To find a simple and robust method for adjusting ante-natal clinic data on HIV prevalence to represent prevalence in the general female population in the same age range, allowing for fertility differences by HIV status. HIV prevalence comparisons for pregnant women and women in the general community show that prevalence in the latter is significantly higher than in the former. An adjustment procedure is needed that is specific for the demographic and epidemiological circumstances of a particular population, making maximum use of data that can easily be collected in ante-natal clinics or are widely available from secondary sources. Birth interval length data are used to allow for subfertility among HIV-positive women. To allow for infertility, relative HIV prevalence ratios for fertile and infertile women obtained in community surveys in populations with similar levels of contraception use are applied to demographic survey data that describe the structure of the population not at risk of child-bearing. For populations with low contraception use, the procedure yields estimates of general female HIV prevalence of 35-65% higher than the observed ante-natal prevalence, depending on population structure. Results were verified using general population prevalence data collected in Kisesa (Tanzania) and Masaka (Uganda). For high contraception use populations, adjusted values range from 15% higher to 5% lower, but only limited verification has been possible so far. The procedure is suitable for estimating general female HIV prevalence in low contraception use populations, but the high contraception variant needs further testing before it can be applied widely.

Estimates of maternal mortality by the sisterhood method in rural nothern Tanzania: a household sample and an antenatal clinic sample.

To estimate maternal mortality in two samples of a population in northern Tanzania. Rural communities and antenatal clinics, Mbulu and Hanang districts, Arusha region, Tanzania. From a household survey 2,043 men and women aged 15-60, and from an antenatal clinic survey 4,172 women aged 15-59. The indirect sisterhood method. The risk of maternal deaths per 100,000 live births (maternal mortality ratio), and the lifetime risk of a maternal death. The risk of a maternal death per 100,000 live births was 362 (95% CI 269-456) and 444 (95% CI 371-517) for the household and antenatal clinic surveys, respectively. The lifetime risk of maternal death was 1 in 38 and 1 in 31, respectively, for the two surveys. A significantly lower risk of maternal death was observed for the respondents attending antenatal clinics closer to the hospital than for those attending clinics further away: 325 (95% CI 237-413) compared with 561 (95% CI 446-677) per 100,000 live births. Lifetime risk of maternal death was 1 in 42 and 1 in 25, respectively. The risk of maternal death per 100,000 live births in this area were comparatively high, but in our survey substantially lower than in previous surveys in Tanzania. Increasing distance from the antenatal clinics to the hospital was associated with higher maternal mortality. There was no significant difference between results based on household and antenatal clinic data, suggesting that accessible health facility data using the sisterhood method may provide a basis for local assessment of maternal mortality in developing countries.

The Relation of Maternal Weight to the Blood Pressures of Gambian Children

The objective of the study was to relate blood pressure levels in children to their mother's weight in pregnancy. The blood pressures of 675 children aged from one to nine years in three villages in rural Gambia were measured. They were matched to antenatal clinic data which had been collected from all pregnant women in the three villages since 1980. Among children under eight years of age those born in the dry season had the highest blood pressures and were heavier. Their blood pressures were positively related to body weight and to mothers' weight at six months of pregnancy. These relationships were independent of mothers' age and parity, birthweight, gestational age, and placental weight. Among older children, aged eight and nine years, those born in the rainy season had the highest blood pressures. Their blood pressures were not related to their mothers' weight at six months of pregnancy. Rather they were inversely related to mothers' weight gain in the last trimester. An interpretation of these findings is that among young children differences in blood pressure are largely determined by rates of maturation. However, the long-term effects of adverse intra-uterine influences which elevate blood pressure become apparent in older children.