Thus, in this study, we aimed to investigate the impact of maternal overweight/obesity on: (1) fetal-newborn growth and body composition during two gestational periods and postpartum, (2) H19DMR methylation in maternal and umbilical cord blood, maternal decidua and placental villi tissues, (3) the expression of H19 and IGF2 genes in the maternal decidua and placental villi tissues, and (4) the relationship between DNA methylation and gene expression in different maternal and fetal tissues with fetal-newborn growth and body composition. Here, H19 is linked to obesity due to melanocortin 4 receptor deficiency.