Mother to child transmission of HIV 1 infection during exclusive breastfeeding in the first 6 months of life: an intervention cohort study
BACKGROUND Exclusive breastfeeding, though better than other forms of infant feeding and associated with improved child survival, is uncommon. We assessed the HIV 1 transmission risks and survival associated with exclusive breastfeeding and other types of infant feeding. METHODS 2722 HIV infected and uninfected pregnant women attending antenatal clinics in KwaZulu Natal, South Africa (seven rural, one semiurban, and one urban) were enrolled into a non randomised intervention cohort study. Infant feeding data were obtained every week from mothers, and blood samples from infants were taken monthly at clinics to establish HIV infection status. Kaplan Meier analyses conditional on exclusive breastfeeding were used to estimate transmission risks at 6 weeks and 22 weeks of age, and Cox's proportional hazard was used to quantify associations with maternal and infant factors. FINDINGS 1132 of 1372 (83% infants born to HIV infected mothers initiated exclusive breastfeeding from birth. Of 1276 infants with complete feeding data, median duration of cumulative exclusive breastfeeding was 159 days (first quartile [Q1] to third quartile [Q3] 122 174 days) 14.1% (95% CI 12.0 16.4) of exclusively breastfed infants were infected with HIV 1 by age 6 weeks and 19.5% (17.0 22.4) by 6 months; risk was significantly associated with maternal CD4 cell counts below 200 cells per muL (adjusted hazard ratio [HR] 3.79; 2.35 6.12) and birthweight less than 2500 g (1.81, 1.07 3.06) Kaplan Meier estimated risk of acquisition of infection at 6 months of age was 4.04% (2.29 5.76) Breastfed infants who also received solids were significantly more likely to acquire infection than were exclusively breastfed children (HR 10.87, 1.51 78.00, p=0.018) as were infants who at 12 weeks received both breastmilk and formula milk (1.82, 0.98 3.36, p=0.057) Cumulative 3 month mortality in exclusively breastfed infants was 6.1% (4.74 7.92) versus 15.1% (7.63 28.73) in infants given replacement feeds (HR 2.06, 1.00 4.27, p=0.051) INTERPRETATION The association between mixed breastfeeding and increased HIV transmission risk, together with evidence that exclusive breastfeeding can be successfully supported in HIV infected women, warrant revision of the present UNICEF, WHO, and UNAIDS infant feeding guidelines.
The Lancet