Maternal stress during pregnancy can impact offspring health, increasing the risk of neuropsychiatric disorders. The human placenta plays a crucial role in understanding this effect, influencing fetal programming as it connects maternal and fetal circulation. Our hypothesis centers on maternal stress influencing children’s outcomes through placental DNA methylation, targeting three cortisol-regulating genes: NR3C1, FKBP5, and HSD11B2.
In this pilot study, chorionic villi and maternal decidua placental layers from 45 mother-infant dyads (divided into two groups based on high/low maternal stress exposure) were analyzed for DNA methylation at the genes of interest via targeted bisulfite sequencing. Pregnant women provided four saliva samples throughout a day for cortisol determinations and were assessed for the presence of depressive symptoms at each of the three trimesters of pregnancy. Newborns underwent neurodevelopmental assessments and salivary cortisol evaluations at 7 weeks.
Increased maternal diurnal cortisol levels in the first trimester of pregnancy was significantly associated with elevated DNA methylation at exon 1D of the NR3C1 gene and lower DNA methylation at intron 7 of the FKBP5 gene, both in chorionic villi samples. Elevated DNA methylation at introns 1 and 7 of FKBP5 in the maternal decidua were strongly linked to an anticipated delivery. DNA methylation at the HSD11B2 promoter region was uniformly low across all placental samples. No associations with newborn neurodevelopment were found.
These results emphasize the importance of exploring layer-specific methylation differences at distinct pregnancy stages, highlighting the complex interplay between maternal stress, placental epigenetic modifications, and fetal development throughout the prenatal period.