Effects of preterm birth, maternal ART and breastfeeding on 24-month infant HIV-free survival in a randomized trial.

BACKGROUND:IMPAACT 1077BF/FF compared the safety/efficacy of two HIV antiretroviral therapy (ART) regimens to zidovudine (ZDV) alone during pregnancy for HIV prevention. PROMISE found an increased risk of preterm delivery (<37 weeks) with antepartum triple ART (TDF/FTC/LPV+r or ZDV/3TC/LPV+r) compared to ZDV alone. We assessed the impact of preterm birth, breastfeeding and antepartum ART regimen on 24-month infant survival. METHODS:We compared HIV-free and overall survival at 24-months for liveborn infants by gestational age, time-varying breastfeeding status, and antepartum ART arm at 14 sites in Africa and India. Kaplan-Meier survival probabilities and Cox proportional hazards ratios (HR) were estimated. RESULTS:3,482 live-born infants (568 [16 3%] preterm and 2,914 [83 7%] term) were included. Preterm birth was significantly associated with lower HIV-free survival (0·85; 95% CI: 0·82-0·88) and lower overall survival (0·89; 95% CI: 0·86-0·91) versus term birth (0·96; 95% CI: 0·95-0·96). Very preterm birth (<34 weeks) was associated with low HIV-free survival (0·65; 95% CI: 0·54-0·73) and low overall survival (0·66; 95% CI: 0·56-0·74). Risk of HIV infection or death at 24-months was higher with TDF-ART than ZDV-ART (adjusted HR 2·37; 95% CI: 1·21-4·64). Breastfeeding initiated near birth decreased risk of infection or death at 24 months (adjusted HR 0·05; 95% CI: 0·03-0·08) compared to not breastfeeding. CONCLUSION:Preterm birth and antepartum TDF-ART were associated with lower 24-month HIV-free survival compared to term birth and ZDV-ART. Any breastfeeding strongly promoted HIV-free survival, especially if initiated close to birth. Reducing preterm birth and promoting infant feeding with breastmilk among HIV/ARV-exposed infants remain global health priorities.