HIV-positive children are still born in Europe despite low mother-to-child transmission (MTCT) rates. We aimed to clarify the remaining barriers to the prevention of MTCT. By combining the national registers, we identified all women living with HIV delivering at least one child during 1983-2013. Of the 212 women delivering after HIV diagnosis, 46% were diagnosed during the pregnancy. In multivariate analysis, age >30 years (P = 0.001), sexual transmission (P = 0.012), living outside of the metropolitan area (P = 0.001) and Eastern European origin (P = 0.043) were risk factors for missed diagnosis before pregnancy. The proportion of immigrants increased from 18% before 1999 to 75% during 2011-2013 (P