Changes in maternal behavior during gestation in the mouse

Four independent groups of 20 naïve female mice, pregnant for the first time, were given a standard test for maternal behavior, respectively, on days 1, 4, 14, and 19 of gestation. Twenty naïve virgins served as controls. The total time giving maternal behavior during the test showed an unexpected and considerable drop on the first day of gestation followed by a progressive increase. The virgin control level was regained and exceeded in between the 4th and the 14th day but remained fairly constant on the 19th and last day of gestation. The change with the advance of gestation merely consisted of a decline in initial sniffing and of an increase in cleaning the pup. Nest-building and crouching showed smaller and irregular changes but retrieving seemed unaffected. In a second experiment 20 newly parturient females were given the same standard test. Initial sniffing of the test pup went on decreasing after parturition. The data are compared with similar findings on rats and hamsters. Attention is drawn to the fact that among the different maternal activities merely those depending upon olfactory stimulation are affected by gestation in the mouse. © 1971.SCOPUS: ar.j