Maternal anxiety during pregnancy and the lack of fetal DNA methylation in cord blood

More than 15% of mothers suffer from an anxiety disorder during pregnancy, an occurrence that has been associated with such adverse outcomes as preterm birth, “small for gestational age” status, and a high risk of emotional and behavioral problems in the child. Previous studies from our group and our collaborators have revealed methylation to be a relevant epigenetic mediator of the link between maternal mental health and child mental health outcomes in the Finland-based PREDO cohort. To expand upon such studies, an epigenome-wide association study (EWAS) was performed to confirm if there is an association between maternal anxiety during pregnancy and cord blood methylation across 15 mother-child cohorts worldwide. This study focused on both general anxiety and pregnancy-related anxiety. Surprisingly, no significant associations were found between maternal anxiety during pregnancy and cord blood methylation in our EWAS, even with nearly 6700 mother-child dyads across 15 cohorts. There could be several reasons for this unexpected result, including the relatively small sample sizes used, possible heterogeneity in maternal exposure to anxiety, and inapt choice of the epigenetic marker. Future studies should aim to include an even larger population size to better analyze the relationship between maternal anxiety during pregnancy and cord blood DNA methylation.