Maternal caffeine consumption during pregnancy and offspring cord blood DNA methylation: an epigenome-wide association study meta-analysis.

Current guidelines recommend pregnant women to limit caffeine intake to less than 200 mg daily, even though there is no clear proof of its effects on human development. A biological explanation for how exposure to caffeine during pregnancy influences development would help clarify if recommended limits are justified. An epigenetic mechanism, called DNA methylation (DNAm), has been suggested as a potential biological explanation for how caffeine intake during pregnancy influences health development. DNAm can switch genes 'on' or 'off' in response to environmental influences and therefore act as a bridge between genes and the environment. Studies have found that smoking during pregnancy is connected to over 6000 changes in DNAm at birth, with lasting effects into adulthood. To explore the link between caffeine intake during pregnancy and DNAm at birth, we analyzed data from 3725 mother­child pairs living in different European countries. We looked at effects from coffee, tea and cola intake during pregnancy on children's DNAm at birth. We found one change in DNAm to be connected to total caffeine and another to cola consumption during pregnancy. These few connections do not provide convincing evidence that caffeine intake during pregnancy impacts children's DNAm at birth. However, because mothers in our study consumed little caffeine, it is possible that results would be different in studies with participants consuming high amounts of caffeine during pregnancy. Potentially, our study did not include enough people to find very small changes in DNAm that are connected to caffeine consumption during pregnancy.