Mouse helpers ensure maternal-infant survival

Summary Parental care is required for offspring survival, because infants require nearly-continual oversight for extensive periods. Parents must balance caretaking with their own survival, and benefit from help provided by other experienced adults. We built a system for 24/7 long-term monitoring of wild-type or oxytocin receptor knockout (OXTR-KO) mouse mothers (‘dams’) over litters. Some wild-type dams had high litter survival rates, but others consistently lost pups due to neglect and hypothermia. Maternal caretaking in low-pup-survival dams improved after co-housing with an experienced dam and litter, from reorganized maternal behavior including increased nest-building. In contrast, singly-housed OXTR-KOs died in childbirth and pups died due to prolonged parturition. Co-housing with a lactating female prevented OXTR-KO maternal-infant mortality, because the other female acted as a ‘midwife’ by removing and cleaning pups from the pregnant dam. Thus for single mothers that continually lose litters or die in labor, maternal-infant survival is enhanced by experienced helpers.