Background: The purpose of the study was to estimate rates of mother-to-child transmission (MTCT) of HIV in the Amazonas, Brazil, and to identify the associated factors.

Methods: This was a retrospective cohort study of 1210 children born to HIV-infected women between 1999 and 2011 and enrolled before age of 18 months in a reference HIV/AIDS pediatrics service in Manaus. We used multivariable logistic regression to assess the effect of maternal, obstetric and prophylactic interventions on MTCT of HIV.

Results: Ten children were excluded because of undocumented maternal HIV status. Among 1200 children, 163 (13.6%) were lost to follow-up. We included in the analysis 1037 children with known HIV status. Of those, 68 children were HIV infected, resulting in a MTCT rate of 6.6% [95% confidence interval (CI): 5.3-8.3]. Among mothers, 76.1% had received antiretroviral therapy during pregnancy, 59.3% elective caesarean, and 9.7% were breastfed. Factors associated with lower odds of MTCT of HIV were antiretroviral therapy during pregnancy [odds ratio (OR): 0.26; 95% CI: 0.12-0.58], elective caesarean (OR: 0.48; 95% CI: 0.23-0.98) and with MTCT: being breastfed (OR: 4.56; 95% CI: 2.19-9.50). Transmission decreased from 7.5% in 2007-2008 to 3.2% in 2011, while breastfeeding decreased from 30.8% in 1999-2000 to 3.9% in 2011-2012.

Conclusions: The HIV rate of MTCT is still high in the Amazonas and challenges for its prevention prevail including lost to follow-up and gaps in critical strategies such as antiretroviral use during pregnancy. More efforts are needed to increase the number of women and babies who successfully complete the prevention of MTCT cascade and work toward elimination of MTCT of HIV.