Providing a diet containing only maintenance levels of energy and protein during the latter stages of pregnancy resulted in a prolonged delivery time during parturition in rats

Abstract

In mammals, a prolonged delivery time during parturition is dangerous for both mother and fetus, although the mechanisms that prolong delivery are unclear. To investigate whether nutrition affects delivery time, we administered two feeds containing maintenance (L-feed) or higher (H-feed) levels of energy and protein at different points during the latter half of pregnancy and compared the effects of the various treatments on delivery time in rats. After the rats had been maintained on the L-feed and then copulated on pro-oestrus (Day 0), pregnant females were randomly allocated to one of three groups: (1) the no-improvement group, which was fed L-feed throughout gestation; (2) the early group, which was fed L-feed until Day 11 of gestation and then switched to H-feed; and (3) the late group, which was fed L-feed until Day 16 of gestation and then switched to H-feed. There was no significant difference in the number of pups among the three groups. However, delivery time was significantly longer in the no-improvement group (73.7 ± 5.2 min) than the early (46.9 ± 5.6 min) and late (55.4 ± 5.5 min) groups. Consuming a maintenance diet during the latter half of pregnancy resulted in a prolonged delivery time.