Adjuvanted vaccines in pregnancy: no evidence for effect of the adjuvanted H1N1/09 vaccination on occurrence of preeclampsia or intra-uterine growth restriction.

Objective: During the H1N1/09 pandemic, pregnant women in the Netherlands were vaccinated with an adjuvanted vaccine. During pregnancy, the maternal immune system changes to enable placental development and growth and acceptance of the semi-allogeneic fetus. As an adjuvant is a pro-inflammatory substance, it may interfere with these immunological changes, resulting in poor placentation or placental growth, which may result in preeclampsia (PE) and fetal intra-uterine growth restriction (IUGR).