Elsevier

The Lancet

Volume 354, Issue 9177, 7 August 1999, Pages 471-476
The Lancet

Early Report
Influence of infant-feeding patterns on early mother-to-child transmission of HIV-1 in Durban, South Africa: a prospective cohort study*

https://doi.org/10.1016/S0140-6736(99)01101-0Get rights and content

Summary

Background

The observation that mother-to-child transmission of HIV-1 can occur through breastfeeding has resulted in policies that recommend avoidance of breastfeeding by HIV-1-infected women in the developed world and under specific circumstances in developing countries. We compared transmission rates in exclusively breastfed, mixedfed, and formula-fed (never breastfed) infants to assess whether the pattern of breastfeeding is a critical determinant of early mother-to-child transmission of HIV-1.

Methods

We prospectively assessed infant-feeding practices of 549 HIV-1-infected women who were part of a vitamin A intervention trial in Durban, South Africa. The proportions of HIV-1-infected infants at 3 months (estimated by use of Kaplan-Meier life tables) were compared in the three different feeding groups. HIV-1 infection was defined by a positive RNA-PCR test.

Findings

At 3 months, 18·8% (95% CI 12·6–24·9) of 156 never-breastfed children were estimated to be HIV-1 infected compared with 21·3% (17·2–25·5) of 393 breastfed children (p=0·5). The estimated proportion (Kaplan-Meier) of infants HIV-1 infected by 3 months was significantly lower for those exclusively breastfed to 3 months than in those who received mixed feeding before 3 months (14·6% [7·7–21·4] vs 24·1% [19·0–29·2], p=0·03). After adjustment for potential confounders (maternal CD4-cell/CD8-cell ratio, syphilis screening test results, and preterm delivery), exclusive breastfeeding carried a significantly lower risk of HIV-1 transmission than mixed feeding (hazard ratio 0·52 [0·28–0·98]) and a similar risk to no breastfeeding (0·85 [0·51–1·42]).

Interpretations

Our findings have important implications for prevention of HIV-1 infection and infant-feeding policies in developing countries and further research is essential. In the meantime, breastfeeding policies for HIV-1-infected women require urgent review. If our findings are confirmed, exclusive breastfeeding may offer HIV-1-infected women in developing countries an affordable, culturally acceptable, and effective means of reducing mother-to-child transmission of HIV-1 while maintaining the overwhelming benefits of breastfeeding.

Introduction

Since the discovery that HIV-1 can be transmitted through breastfeeding, several policy recommendations have been developed,1, 2 which are expected to have a global impact on maternal and infant health. Whether prevention of HIV-1 infection through avoidance of breastfeeding will in practice outweigh the adverse effects of not breastfeeding has yet to be discovered. Breastfeeding by HIV-1-infected women in more-developed countries has virtually ceased3 and in less-developed countries many thousands of seropositive women and women who believe they may be HIV-1 infected are expected to avoid breastfeeding. The cultural diffusion theory raises the possibility that a loss of confidence in breastfeeding will spread to all women.4

Advocates of child care consider breastfeeding to be one of the principal gains to current maternal and child health, regained through long-standing campaigns to protect mother and infant wellbeing. The reason why breastfeeding is believed to be pre-eminent in human nutrition derives from its well-recognised nutritional, immunological, social, psychological, and nurturing benefits, which are especially important in the first 3 months.5

Analyses of HIV-1 transmission via breastmilk are flawed because they have failed to account for the effects of different types of breastfeeding practices: exclusive or mixed breastfeeding (without or with water, other fluids, and foods that might contaminate and injure the immature gastrointestinal tract).6 Two studies have attempted to examine the effect of different breastfeeding patterns on mother-to-child transmission,7, 8 but both have limitations. The most widely quoted meta-analysis on the risks of mother-to-child transmission by breastfeeding6 depended on studies with small sample sizes, short breastfeeding durations, and studies that do not distinguish exclusive from mixed breastfeeding.

We prospectively examined the impact of different patterns of breastfeeding on mother-to-child transmission of HIV-1 at 3 months of age.

Section snippets

Design

The mother-infant pairs enrolled in this study were participating in a vitamin A intervention trial to reduce the rate of mother-to-child transmission of HIV-1. The study took place at antenatal clinics of two hospitals in Durban, South Africa (King Edward VIII Hospital and McCord Hospital). Women were recruited between July, 1995, and April, 1998, and were randomly assigned vitamin A (daily supplement containing 5000 IU retinyl palmitate and 30 mg β-carotene) or placebo. Women started

Study sample

661 women recruited into the vitamin A trial were known to have had a liveborn infant at one of the two study hospitals (631 women had singletons, 28 women had twins, and two women delivered a single infant after death of the co-twin in utero; figure). Among the 631 singletons, 79 (12·5%) were not followed up for long enough to establish their feeding practices, and three were followed up but had no HIV-1 test results available. The remaining 549 singletons were included in the analysis. Those

Discussion

Our results do not accord with conventional wisdom because they suggest that the vertical transmission of HIV-1 through breastmilk is dependent on the pattern of breastfeeding and not simply on all breastfeeding. Exclusive breastfeeding carries a significantly lower risk (almost half the risk) of mother-to-child transmission of HIV-1 than mixed feeding. Although the risks of HIV-1 transmission associated with non-exclusive breastfeeding seem to be substantial (risk of HIV-1 infection by 3

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