Objective: To evaluate the risk of postnatal HIV transmission among women in Abidjan, Côte d'Ivoire offered alternatives to prolonged breastfeeding, and to assess the impact of the breastfeeding pattern and duration on this risk.
Methods: In 2001-2003, HIV-infected pregnant women received peri-partum antiretroviral prophylaxis and were counselled antenatally regarding infant feeding options: formula feeding or exclusive breastfeeding with early cessation from 4 months of age. The primary outcome was HIV postnatal transmission by 18 months of age, defined by a positive HIV test after a negative test > or =30 days. The effect of the pattern (mixed feeding, defined as breastmilk plus food-based fluid, solid food or non-human milk) and duration (less vs. more than 6 months) of breastfeeding on postnatal transmission was assessed.
Results: Of 622 live-born infants who were HIV uninfected at or after 30 days, 15 were infected postnatally, 13/324 among breastfed, and 2/298 among formula-fed infants. The 18-month probability of remaining free from HIV infection was 0.95 [95% CI, 0.92-0.97] and 0.99 [95% CI, 0.97-1.00] in the breastfeeding and formula-feeding groups respectively (p<0.001). In adjusted analysis, breastfeeding for more than 6 months and mixed feeding during the first month of life were independently associated with a 7.5 (AOR 95% CI, 2.0-28.2, p=0.003)- and a 6.3 (95% CI, 1.1-36.4, p=0.04)-fold increase of postnatal transmission among breastfed children.
Conclusions: Mixed feeding during the first month of life and breastfeeding beyond 6 months are strong determinants of HIV transmission and should be avoided when replacement feeding after breastfeeding cessation can be safely and sustainably provided.