RESUMO
Seventy nulliparous women were investigated by needle electromyography of the pelvic floor muscles to establish whether childbirth causes damage to the pelvic floor muscles and its nerve supply and to establish the neurophysiological parameters to diagnose such conditions. It was found that women with long second stage of labor and heavier babies showed definite evidence of denervation in EMG. However, forceps delivery and perineal tears did not contribute to the degree of denervation. It was concluded that labor [vaginal delivery and cesarean section after trial of labor] causes partial denervation with consequent reinnervation in most women having their first baby. In six women, the damage is serve and associated with urinary and fecal incontinence