The Pelvic Floor During Pregnancy and after Childbirth, and the Effect of Pelvic Floor Muscle Training on Urinary Incontinence - A Literature Review

Pregnancy and especially vaginal childbirth are risk factors for pelvic floor dysfunctions such as urinary incontinence (UI). The aim of this literature review was to give an overview of how the pelvic floor may be affected by pregnancy and childbirth, and further state the current evidence on pelvic floor muscle training (PFMT) on UI. Connective tissue, peripheral nerves and muscular structures are already during pregnancy subjected to hormonal, anatomical and morphological changes. During vaginal delivery, the above mentioned structures are forcibly stretched and compressed. This may initiate changed tissue properties, which may contribute to altered pelvic floor function and increased risk of UI. Trained pelvic floor muscles (PFM) may counteract the hormonally mediated increased laxity of the pelvic floor and the increased intra-abdominal pressure during pregnancy. Further, a trained PFM may encompass a greater functional reserve so that childbirth does not cause the sufficient loss of muscle function to develop urinary leakage. Additionally, a trained PFM may recover better after childbirth as the appropriate neuromuscular motor patterns have already been learned. Evidence based guidelines recommend that pregnant women having their first child should be offered supervised PFMT, and likewise for women with persistent UI symptoms after delivery (Grade A recommendations). Conclusion: Several observational studies have demonstrated significantly higher PFM strength in continent women than in women having UI, and further that vaginal delivery weakens the PFM. Current evidence based guidelines state that PFMT can prevent and treat UI, and recommend strength training of the PFM during pregnancy and postpartum.