The influence of maternal size on placental area and foal birthweights in the mare

Abstract

The influence of maternal size on foal birthweights and the total microscopic area of fetomaternal contact at the placental interface was studied by comparing placentae from normal Thoroughbred-in-Thoroughbred and Pony-in-Pony control pregnancies with those from between-breed Thoroughbred-in-Pony (deprived in utero environment) and Pony-in-Thoroughbred (luxurious in utero environment) pregnancies created by embryo transfer. Strong positive correlations were revealed between foal birthweight and both the gross area of the placenta and the total microscopic area of fetomaternal contact via the microcotyledons. The results highlight the importance of the intrauterine environment for the growth and development of the equine fetal foal.