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Patterns of body composition among HIV-infected, pregnant Malawians and famine effects

Summary of research¹

Mothers attending antenatal clinic

Few studies have examined maternal anthropometry and its predictors during pregnancy in sub-Saharan Africa in the context of HIV/AIDS. In resource-limited countries, exposure to inadequate dietary intake, frequent reproductive cycles, infectious disease, and demanding physical labour may alter women’s body composition dynamics during pregnancy compared to what is seen among women in countries where these stresses are mostly absent. The importance of seasonality to reproductive health is emphasized by several studies across Africa. Among predominantly HIV uninfected populations in Africa, lower gestational weight gain and increased maternal morbidity have been associated with the rainy season, which is often characterized by increased food shortage, physical labour, and malarial infection rates. Because loss of lean body mass has been shown to be a predictor of HIV survival, independent of CD4 count, it is important to describe the changes in body composition throughout pregnancy and to identify its key determinants in HIV-infected populations.

A recently published study hypothesized that midupper arm circumference (MUAC), arm muscle area (AMA) and arm fat area (AFA) would decrease in HIV infected populations, given the tendency for maternal wasting combined with the increased effects of food shortage, physical labour, and infection rates during the rainy seasons. The researchers analyzed repeated anthropometrics from HIV-1 infected pregnant Malawian women to evaluate two primary objectives: (1) to describe patterns of change in maternal weight, MUAC, AMA, and AFA among HIV infected pregnant women, and (2) to identify potential seasonal, CD4 count, and socio-demographic factors, including age, parity, marital status, wealth, and the educational level and occupation of both the mother and her partner, as predictors of maternal anthropometrics in this population.

The study was based on a secondary data analysis, including prenatal women who consented and met predelivery screening criteria between April 2004 and August 2006 for the Breastfeeding, Anti-retrovirals, and Nutrition (BAN) Study, a postnatal clinical trial. The data for the analysis were derived from surveys conducted to screen women who consented to be in the BAN Study and to collect baseline demographic, anthropometric, dietary, and health status data during antenatal care and at delivery. Study participants were recruited from four sites with outreach to all pregnant women in Lilongwe, Malawi.

By August 2006, 1,745 women met initial antenatal screening criteria: > or =14 years of age, no prior antiretroviral medication use, < 30 weeks gestation, and no serious complications of pregnancy. Of these, 1,336 women returned for the second antenatal screening visit approximately 1 week later and met eligibility criteria based on blood test results: HIV positive status, CD4 count =200 cells/dL, haemoglobin =7 g/dL, and normal liver function tests (=2.5 times the upper limit of normal). At the second antenatal visit (the baseline visit), eligible women completed a baseline interview and physical exam. Of the 1,336 eligible women at the baseline visit, 168 were missing a height measurement and 38 were missing another key baseline factor. Therefore, there were 1,130 women available for this analysis. The sample size of 1,130 was determined to be sufficient to detect a 1 unit difference in the main outcomes with 90% power.

None of the women took antenatal antiretrovirals during this or prior pregnancies. In accordance with national guidelines from Malawi’s Ministry of Health on initiation of antiretroviral treatment, these women did not qualify for treatment due to their high CD4 count levels. Additionally, at the time, Malawi’s national guidelines on prevention of mother to child transmission of HIV did not include antiretroviral prophylaxis during pregnancy. Data were collected on interim malarial infections but were not available for all participants. All women received iron and folate supplements, screening for anaemia, malaria prophylaxis, and mosquito nets.

The BAN Study protocol was approved by the Malawi National Health Sciences Research Committee and the institutional review boards at the University of North Carolina at Chapel Hill and the U.S. Centres for Disease Control and Prevention.

Gestational ages at baseline and subsequent prenatal visits were derived from the date of last menstrual period (LMP) or if LMP was unknown, the first available fundal height (FH).

Weight, height, MUAC and triceps skinfold thickness were measured at each visit by trained BAN nutrition staff. For MUAC and skinfolds, quality assurance checks were performed periodically to ensure consistent inter- and intra-reliability of measurements. Weight was measured to the nearest 100 g at each visit. MUAC was measured to the nearest 0.1 cm. MUAC and triceps skinfold thickness were used to AMA, an indicator of muscle mass, and AFA, an indicator of fat mass. CD4 count was measured as a cross-section during the first screening visit.

In Malawi, food availability, malnutrition, and infectious disease morbidity vary substantially by season due to cycles of rainfall and agricultural production. The famine season, locally referred to as the ‘Green Famine’, extends from August to March and includes the rainy season prior to the harvest. This time period is marked by limited food availability as stores of the previous year’s crops are depleted and incidence of infectious diseases peaks. Exposure to the famine season was measured as the number of days during the month prior to each measurement that were spent in the famine season.

Basic socio-demographic information was collected during the baseline interview: age, parity, marital status, household characteristics, and the educational level and occupation of both the mother and her partner. Wealth was defined based on a wealth index, derived from principal components analysis (PCA) of household characteristics. The different categories or levels of wealth were represented by index quintiles. Depending upon the estimated gestational age at baseline (range: 12–30 weeks), women were asked to return for follow- up prenatal care at approximately 28, 32, and 36 weeks gestation. The average gestational age at each follow-up visit was 29, 33, and 36 weeks, and the number of participants at these visits was 694, 868, and 703, respectively. More than 90% of the sample had at least 2 visits. The average time between visits was 4.5 weeks (Standard Deviation (SD) = 2.8). The average total time between the baseline and last followup visits was 10.4 weeks (SD = 5.1). The time between the last antenatal visit and delivery ranged from 0 to 10 weeks because in a few cases, the last visit coincided with the delivery date. The analyses therefore reflected changes during the later stages of pregnancy.

Results

A crude analysis of weight change over the 2,338 intervals between consecutive prenatal visits indicated that 17.3% of intervals showed weight loss. About half of intervals also had a loss in AMA (48.7%) and AFA (53.1%). Of those intervals in which muscle stores were lost, 34.3% lost both muscle and fat stores. The prevalence of wasting (MUAC<22 cm) was 1.9%, 3% of women gained no weight, 8.4% showed weight loss, and 59% had low fat stores (AFA<20 cm2). Most women in this sample were young with low parity. The median baseline CD4 count was 439 (inter-quartile range: 319–592) per 100 cells/dL. Average maternal weight, MUAC, AMA, and AFA at baseline was 58.7 kg (SD = 8.2), 26.5 cm (SD = 2.7), 36.7 cm2 (SD = 6.5), and 19.7 cm2 (SD = 8.1), respectively.

In bivariate linear analysis, maternal weight increased at a rate of 0.24 kg per gestational week. There was no evidence of change in MUAC, while an increase was noted for AMA and a decline was noted for AFA. In multivariate analysis, weight increased at a rate of 0.27 kg per gestational week and AFA decreased at a rate of 0.06 cm2 per gestational week. Exposure to the famine season was also associated with decreased weight gain and loss of AFA per week of pregnancy. CD4 count, as a continuous variable, was directly associated with MUAC, AFA, and weight. Each 100 cells/dL increase in CD4 count was associated with an increase of 0.08 cm (95% CI 0.01, 0.15) in MUAC, 0.15 cm2 (95% CI -0.01, 0.30) in AMA, 0.21 cm2 (0.01, 0.41) in AFA, and 0.24 kg (0.03, 0.45) in weight.

Wealth, occupation, education level, age, and parity were associated with anthropometric changes in MUAC, AMA, AFA, or weight during pregnancy. Women with greater wealth had increased MUAC and AFA while occupation, but not wealth, among women had a significant direct positive association with AMA. Women who completed primary education had higher MUAC due to increased AMA than those who completed secondary or higher level education. Age and parity were positively associated with MUAC and AMA, but only age was associated with weight. AFA was unrelated to age and parity.

Over two-thirds of the women in the study had some exposure to the famine season in the month prior to an anthropometric assessment. Exposure to the famine season negatively impacted weight gain in this study, which is consistent with a report of highest pregnancy weight gain among Malawian women who deliver in July–September (mean gain 0.25–0.30 kg/week) and lowest gain among those who deliver in January-May (mean gain 0.10–0.20 kg/week).

The rate of change in MUAC and AMA during pregnancy was modified by exposure to the famine season. Women with no exposure to famine during the previous month experienced a subtle increase in MUAC and a significant increase in AMA. In contrast, women who spent the entire preceding month in a famine period had a significant decrease in MUAC and AMA per week of gestation.

In conclusion, the findings among HIVinfected, pregnant women are similar to those reported for uninfected women in sub-Saharan Africa. However, effects of the famine season among undernourished, HIV-infected Malawian women are of concern. Strategies to optimise nutrition during pregnancy for these women appear warranted.

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Reference this page

Patterns of body composition among HIV-infected, pregnant Malawians and famine effects. Field Exchange 44, December 2012. p23. www.ennonline.net/fex/44/patterns

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