The relationship between infanticide and pregnancy block in mice.

Newly pregnant mice are more likely to exhibit pregnancy block when females are exposed to infanticidal males rather than to noninfanticidal males. These data suggest that females are able to assess the risk to their future infants and adjust their reproductive tactic. Those females that did not exhibit pregnancy block in the presence of infanticidal males suffered a greater loss of pups than those in the presence of noninfanticidal males, demonstrating the advantage of pregnancy block. Females served by infanticidal or noninfanticidal males showed no difference in pregnancy block, but if the litter was produced, there was a greater loss of pups sired by infanticidal males.