Low rates of mother-to-child transmission of HIV following effective pregnancy interventions in the United Kingdom and Ireland, 2000–2006

AIM: In the United Kingdom (UK) and Ireland, avoidance of breastfeeding and alternative combinations of antiretroviral therapy regimen and mode of delivery are recommended according to maternal clinical status. The aim of this analysis was to explore the impact of different strategies to prevent mother-to-child transmission at a population level. DESIGN: Comprehensive national surveillance study. METHODS: Pregnancies in diagnosed HIV-infected women in the UK and Ireland are notified to the National Study of HIV in Pregnancy and Childhood; infant infection status is subsequently reported. Factors associated with transmission in this observational study were explored for singleton births between 2000 and 2006. RESULTS: The overall mother-to-child transmission rate was 1.2% (61/5151, 95% confidence interval: 0.9-1.5%), and 0.8% (40/4864) for women who received at least 14 days of antiretroviral therapy. Transmission rates following combinations recommended in British guidelines were 0.7% (17/2286) for highly active antiretroviral therapy with planned Caesarean section, 0.7% (4/559) for highly active antiretroviral therapy with planned vaginal delivery, and 0% (0/464) for zidovudine monotherapy with planned Caesarean section (P = 0.150). Longer duration of highly active antiretroviral therapy was associated with reduced transmission after adjusting for viral load, mode of delivery and sex (adjusted odds ratio = 0.90 per week of highly active antiretroviral therapy, P = 0.007). Among 2117 infants born to women on highly active antiretroviral therapy with viral load less than 50 copies/ml, only three (0.1%) were infected, two with evidence of in-utero transmission. CONCLUSION: Sustained low HIV transmission rates following different combinations of interventions in this large unselected population are encouraging. Current options for treatment and delivery offered to pregnant women according to British guidelines appear to be effective.