Highly active antiretroviral therapy (HAART) may be associated with adverse pregnancy outcomes. Among 4372 live births in the European Collaborative Study, the prematurity rate increased to 24.9% in 2000-2004. Antenatal HAART use initiated pre-pregnancy was strongly associated with prematurity (AOR 2.05, 95% CI 1.43, 2.95), particularly severe prematurity. The implication of increased prematurity is evidenced in high neonatal mortality in these groups (0.66% for infants at 34-36 weeks and 7.37% at < 34 weeks' gestation).