Effects of peripheral nerve lesions during pregnancy on parturition in rats.

Bilateral section of either the sensory or motor branch of the pelvic nerve or pudendal nerve was performed in rats on days 8-10 of pregnancy, and the effects on delivery were observed. Bilateral resection of the sensory branch of the pelvic nerve reduced the number of live pups per litter, and increased the number of stillbirths and the number of fetuses retained in utero per litter at day 24. Sectioning motor components of the pelvic nerve, or both motor and sensory components of the pudendal nerve, had no effects on delivery in rats. We conclude that of the peripheral nerves evaluated in this study, only the sensory branch of the pelvic nerve is required for normal vaginal delivery in this species.