Parturition: Its role in the long term retention of maternal behavior in the rat

The role of parturition in the establishment of the long-term retention of maternal behavior in the rat was investigated. Primigravid rats caesarean sectioned on Day 22 of gestation that responded maternally immediately (<22 hr) following surgery were permitted to be maternal towards test pups for 48–70 hr at which time test pups were separated from the experimental animals. When reexposed to rat pups some 25 days later 50% of the caesarean sectioned animals responded maternally within 1 hr while the remaining 50% responded maternally within 5 test days. The level of maternal responsiveness of caesarean sectioned animals did not differ from that of primiparous animals given only 2 days of pup exposure postpartum and then tested for the retention of maternal behavior 25 days later. Forty-two percent of the primiparous animals responded maternally during the first test period 25 days following litter removal. Although a slight reduction in latency to respond maternally was evident in nulliparous animals upon reexposure to rat pups 25 days after an initial sensitization period, both caesarean sectioned and primiparous animals responded maternally significantly faster than did previously sensitized nulliparous females. The data demonstrate that the act of parturition is not essential for the establishment of the long-term retention of maternal behavior in the rat, and suggest that exposure to pups following termination of pregnancy may serve to intensify the process whereby the retention of maternal behavior is established.