Ross KM, et al. - Researchers investigated if pregnancy itself and an important pregnancy-associated variables, alterations in body mass index (BMI) between pregnancy and the postpartum period, are related to epigenetic aging. As part of the Healthy Babies Before Birth project, a pilot sample of 35 women were selected. At mid-pregnancy and 1-year postpartum, whole blood samples were obtained. An online calculator was employed to calculate epigenetic age indices. From pregnancy to one year following birth, women became younger with respect to phenotypic epigenetic age, GrimAge, DNAm PAI-1, and epigenetic age indices associated to aging-related changes in immune cell populations, known as extrinsic epigenetic age. It implies that depending on particular epigenetic age indices, women seemed to become younger from pregnancy to the postpartum period. BMI at one year post-birth, that indicates weight retention, was identified as a predictor of greater epigenetic aging during this period.