Uterine and placenta characteristics during early vascular development in the pig from day 22 to 42 of gestation.

•Significant morphological changes occur from 27 and 32 days of gestation.•Microfolds at the maternal:fetal interphase and necrotic tips develop by 27 days.•Placenta of small fetuses had less increase in weight than large fetus by 42 days.