Fig 1. Observed relationship between female laboratory mouse behaviors and litter survival.

Nest building, parturition-related behavior, active and passive maternal behavior, ignoring still pup and being outside nest from 24 h before until 24 h after parturition in 64 primiparous mice whose litters survived (solid line; n = 49) and did not survive until weaning (dashed line; n = 15); mean proportion of 30-s observations per 6-h period with at least one occurrence of the behavior.