GLASGOW—Pregnant women who deliver their babies by C-section have higher pelvic floor muscle (PFM) strength, higher vaginal resting pressure, and higher PFM endurance than women who deliver vaginally, researchers reported here at the International Continence Society annual meeting.
Investigators in Norway studied 135 pregnant women, of whom 114 (84.4%) had a vaginal delivery and 21 (15.5%) had a C-section. Among those who delivered vaginally, 13.3% had an instrumental delivery. The researchers, led by Kari Bø, PhD, of the Norwegian School of Sports Sciences in Oslo, measured (in cm H2O) vaginal resting pressure, PFM strength, and PFM endurance at gestational week 22 and six weeks post-partum. Overall, vaginal resting pressure was reduced by 10.6, PFM strength by 15, and PFM endurance by 95.8.
At six weeks post-partum, the vaginal resting pressure was 37.4 among women who delivered by C-section versus 29.2 for those who delivered vaginally. PFM strength was 31.4 in the C-section group compared with 15 in the vaginal delivery group. PFM endurance was 207.1 compared with 101.4. All of these differences were statistically significant. Additionally, among women who delivered vaginally, those who delivered without the aid of instrumentation had significantly higher PFM strength than those who had an instrumental delivery (16.2 vs. 9.4).
The investigators explained that the pelvic floor muscles play a significant role in pelvic organ support. During vaginal delivery, the pubococcygeous part of the levator ani muscle undergoes a stretch estimated to be three times its own length. When striated muscles are forcibly stretched, they noted, general muscle weakness and injury may occur, resulting in reduced ability to contract.