Background:  Debate about breastfeeding among HIV⁺ mothers has primarily considered infant outcomes. However, previously reported data suggesting that prolonged lactation may adversely affect maternal health has added complexity to the debate.      

Methods:  As part of a randomized trial on mode of breastfeeding and postnatal HIV transmission underway in Lusaka, Zambia, we tested whether mortality among HIV⁺ women increased with prolonged breastfeeding. 807 HIV⁺ women who delivered live-born infants were followed until 24 months after delivery; 627 of these women delivered > 12 months before this analysis. For the main study, half of the women were randomly assigned to a counseling program that encouraged abrupt cessation of breastfeeding at 4 months (group A), and the other half to a program that encouraged continued exclusive breastfeeding to 6 months with gradual introduction of weaning foods thereafter (group B). The duration of breastfeeding after 4 months in group B was based on the woman’s personal informed choice.

Results:  In both groups, 95% were still breastfeeding at 4 months. By 12 months, 23% of those assigned to group A (early cessation group) were still breastfeeding compared with 77% among those assigned to group B (continued breastfeeding group). There was no difference in the Kaplan-Meier estimates of mortality between 401 HIV⁺ women assigned to group A (mortality at 12 months 4.8% [95% CI 2.5 to 7.2]) compared with 406 HIV⁺ women assigned to group B (3.9% [95% CI 1.7 to 6.0]), p = 0.14. If analysis was restricted to those women surviving to 4 months, there was also no difference: mortality in group A by 18 months was 5.6% (95% CI 2.5 to 8.7) and in group B 5.1% (95% CI 2.3 to 7.9), p = 0.54. Analysis based on actual practice, rather than random assignment, revealed that those who stopped breastfeeding early had significantly higher mortality than those who breastfed for longer.   

Conclusions:  There was no evidence of increased maternal mortality attributable to long-term breastfeeding in our randomized study. The finding of increased mortality among women who actually ceased breastfeeding early, which is most likely due to confounding by severity of maternal illness, makes it unlikely that failure to comply with random assignment diluted an adverse effect of breastfeeding. Although HIV-related mortality was high, prolonged lactation did not adversely influence survival of HIV⁺ women.

Keywords: mortality; breastfeeding; women