Lactation-associated postpartum weight changes among HIV-infected women in Zambia.

BACKGROUND There are concerns about effects of lactation on postpartum weight changes among HIV-infected women because low weight may increase risks of HIV-related disease progression. METHODS This analysis of postpartum maternal weight change is based on a trial evaluating the effects of shortened breastfeeding on postpartum mother-to-child transmission of HIV in Lusaka, Zambia, in which 958 HIV-infected women were randomized to breastfeed for a short duration (4 months) or for a duration of their own informed choosing (median 16 months). Among 768 women who met inclusion criteria, we compared across the two groups change in weight (kg) and the percent underweight [body mass index (BMI) <18.5] through 24 months. We also examined the effect of breastfeeding in two high-risk groups: those with low BMI and those with low CD4 counts. RESULTS Overall, women in the long-duration group gained less weight compared with those in the short-duration group from 4-24 months {1.0 kg [95% confidence interval (CI): 0.3-1.7] vs 2.3 kg (95% CI: 1.6-2.9), P = 0.01}. No association was found between longer breastfeeding and being underweight (odds ratio 1.1; 95% CI: 0.8-1.6; P = 0.40). Effects of lactation in underweight women and women with low CD4 counts were similar to the effects in women with higher BMI and higher CD4 counts. Women with low baseline BMI tended to gain more weight from 4 to 24 months than those with higher BMI, regardless of breastfeeding duration (2.1 kg, 95% CI: 1.3-2.9; P < 0.01). CONCLUSIONS In this study of HIV-infected breastfeeding women in a low-resource setting, the average change in weight from 4 to 24 months postpartum was a net gain rather than loss. Although longer duration breastfeeding was associated with less weight gain, breastfeeding duration was not associated with being underweight (BMI < 18.5). Weight change associated with longer breastfeeding may be metabolically regulated so that women with low BMI and at risk of wasting are protected from excess weight loss.