Effect of repeated reproductive cycles on pregnancy outcome in ad libitum-fed and chronically food-restricted rats.

To evaluate the combined effects of repeated, closely spaced reproductive cycles and dietary intake on maternal nutritional status and pregnancy outcome, rats were fed ad libitum or 75 or 60% of ad libitum intake. Dietary treatment began 28 d before breeding and continued through two reproductive cycles. Underfed rats gained less weight during pregnancy and had fewer and lighter pups at parturition. During the third week of the first lactation and between weaning and the second conception, underfed rats gained weight, whereas the controls lost weight. Underfed dams gained more weight in the second pregnancy and retained more weight than in the first pregnancy. Dams and pups in all groups were larger at the second parturition. The results indicate that net weight gain both during pregnancy and between reproductive cycles contributed to the ability of underfed dams to produce larger young at the second birth.