Unilateral ovariectomy during pregnancy in well-nourished and undernourished rats: effects on placenta and fetal body and brain growth.

The possibility that maternal unilateral ovariectomy, which is said to enhance fetal growth, might also ameliorate the harmful of undernutrition was investigated. Maternal undernutrition throughout pregnancy and unilateral ovariectomy on day 13 of pregnancy were investigated separately and in combination in primigravid rats with respect to male and female placental and fetal growth. Undernutrition increased the number of fetal resorptions in the 3rd week of pregnancy and depressed placental and fetal weights in both sexes, although there was some relative sparing of fetal brain weight. Unilateral ovariectomy of well-nourished mothers on day 13 of pregnancy caused significant increments in placental weight, and fetal body and brain weight in both sexes, but not in fetal length. None of these effects were observed in underfed mothers; that is, unilateral ovariectomy was ineffective in ameliorating the consequences for the fetus of maternal undernutrition. In none of the groups was there a significant relationship between fetal body weight and the number of fetuses, although in the undernourished litters significant negative correlations between fetal body weight and total number of placentae (normal and supernumerary) were found.