Levator function before and after childbirth

Background: Vaginal childbirth is assumed to affect pelvic floor muscle function as a result of direct trauma and/or neuropathy. Aims: To assess levator function by ultrasound prior to and after delivery and correlate changes with delivery data. Methods: A total of 200 nulliparous women were seen at 6-18 and 32-37 weeks' gestation as well as 2-5 months post-partum. Appointments consisted of an interview, paper towel test, flowmetry and translabial ultrasound (supine and after voiding). The most effective of at least three contractions was used for evaluation according to a previously published method quantifying cranioventral displacement of the bladder neck. Labour and delivery details were collected through data collection sheets and the institutional database. Results: A total of 173 women were seen in late pregnancy; 169 returned on average 93 days post-partum. At the last visit, a reduction of cranioventral lift from 11.2 mm (SD 4.5) to 8.8 mm (SD 4.2) was noted (P < 0.001) which correlated weakly with active second stage (Spearman's r = -0.196, P=0.013), passive second stage (r = -0. 15, P = 0.059) and total second stage of labour (r = -0.225, P = 0.004). Good antenatal levator function was not protective of changes in levator function or pelvic organ support. Conclusions: Childbirth reduces bladder neck displacement on levator contraction. The main obstetric determinant affecting levator function seems to be the length of the second stage. A Caesarean section in the second stage appears to exert no protective effect. It seems to be full engagement of the fetal head, not childbirth itself, that impairs levator function.