Male modulation of female reproductive physiology in Norway rats: effects of mating during postpartum estrus

Like the majority of other male mammals, male rats typically complete several ejaculatory series during mating. Despite earlier evidence to the contrary, it now appears that these multiple series may be crucial for successful reproduction. Thus, in Long-Evans females mated during postpartum estrus, multiple series increased the proportion of females that became pregnant, decreased the proportion with stillborn pups, and decreased the number of stillborn pups per litter.