Adolescent and young pregnant women at increased risk of mother-to-child transmission of HIV and poorer maternal and infant health outcomes: A cohort study at public facilities in the Nelson Mandela Bay Metropolitan district, Eastern Cape, South Africa.

BACKGROUND South Africa (SA) has the highest burden of childhood HIV infection globally, and has high rates of adolescent and youth pregnancy. OBJECTIVE To explore risks associated with pregnancy in young HIV-infected women, we compared mother-to-child transmission (MTCT) of HIV and maternal and infant health outcomes according to maternal age categories. METHODS A cohort of HIV-positive pregnant women and their infants were followed up at three sentinel surveillance facilities in the Nelson Mandela Bay Metropolitan (NMBM) district, Eastern Cape Province, SA. Young women were defined as 24 years old and adolescents as 19 years. The effect of younger maternal age categories on MTCT and maternal and child health outcomes was assessed using log-binomial and Cox regression controlling for confounding, using women aged > 24 years as the comparison group. RESULTS Of 956 mothers, 312 (32.6%) were young women; of these, 65 (20.8%) were adolescents. The proportion of young pregnant women increased by 24% between 2009/10 and 2011/12 (from 28.3% to 35.1%). Young women had an increased risk of being unaware of their HIV status when booking (adjusted risk ratio (aRR) 1.37; 95% confidence interval (CI) 1.21 - 1.54), a reduced rate of antenatal antiretroviral therapy (ART) uptake (adjusted hazard ratio 0.46; 95% CI 0.31 - 0.67), reduced early infant HIV diagnosis (aRR 0.94; 95% CI 0.94 - 0.94), and increased MTCT (aRR 3.07; 95% CI 1.18 - 7.96; adjusted for ART use). Of all vertical transmissions, 56% occurred among young women. Additionally, adolescents had increased risks of first presentation during labour (aRR 3.78; 95% CI 1.06 - 13.4); maternal mortality (aRR 35.1; 95% CI 2.89 - 426) and stillbirth (aRR 3.33; 95% CI 1.53 - 7.25). CONCLUSION An increasing proportion of pregnant HIV-positive women in NMBM were young, and they had increased MTCT and poorer maternal and infant outcomes than older women. Interventions targeting young women are increasingly needed to reduce pregnancy, HIV infection and MTCT and improve maternal and infant outcomes if SA is to attain its Millennium Development Goals.