The effect of cigarette exposure on placental epigenetics: A systematic review.

Tobacco use during pregnancy is a modifiable risk factor contributing to adverse birth outcomes. The placenta is the master regulator of fetal growth and development and contributes to the overall health of the pregnant person and fetus throughout pregnancy. The primary aim of our systematic review was to investigate the impact of tobacco product use during pregnancy on placental epigenetics. A secondary aim of the review was to investigate how tobacco-related alterations in the placental epigenome are associated with maternal and fetal health outcomes. Twenty papers were included in the review. All studies included investigated combustible cigarette smoking only and the majority (85 %) studied full term placentas. Using data from studies that included data on methylation changes in 30 or more CpG loci and/or genes, the three most common molecular pathways identified across all the genes were binding, catalytic activity, and transcription regulator activity. However, a large proportion of the genes were not assigned to a specific category. Additional research is needed to understand whether non-cigarette tobacco products also disrupt placenta epigenetics.