John: Hello, I'm John Hilton, editor in the Cochrane Editorial and Methods department. Many women suffer from incontinence during or after pregnancy, and pelvic muscle exercises are one way to help. In an updated Cochrane Review in December 2017, Stephanie Woodley and Jean Hay-Smith from the University of Otago in New Zealand, and colleagues present the evidence from nearly 40 trials; and they tell us the findings in this podcast.

Stephanie: Urinary incontinence is experienced by more than one-third of women in the second and third trimesters of pregnancy, and about one-third leak urine in the first three months after giving birth. Faecal incontinence is a little less common, but both of these problems have a big impact on quality of life.
We investigated the effects of doing pelvic floor muscle exercises during pregnancy or after birth on incontinence. The exercises may help strengthen the pelvic floor muscles, which span the area between the legs. The muscles support the bladder, bowel and womb, and help stop leakage by closing off the outlets from the bladder and bowel. The exercises strengthen the muscles by contracting them several times in a row, more than once a day, for several days a week over a long period of time.
In this update of the 2012 Cochrane Review, we added 17 trials bringing the total to 38, involving nearly 10,000 women from 20 countries who were allocated randomly to receive pelvic floor muscle exercises or not. 

Jean: Overall, studies were not large and most had design problems, making the overall quality of the evidence no better than low or very low. The exercises differed considerably between studies and were often poorly described, although the findings of the studies were generally consistent. There were insufficient data to be sure about the effects of the exercises on faecal incontinence and so our conclusions are focused on the effects on urinary incontinence for three main groups of women.
We found that women who had no leakage when they started pelvic floor muscle exercises were less likely to have urine leakage during late pregnancy and three to six months after childbirth compared with women who received usual care. That is, doing the exercises prevented urinary incontinence. 
Studies in which women were offered advice on pelvic floor muscle exercises whether they had leakage or not looked for a mixed prevention and treatment effect, and we found that women who began exercising during pregnancy were less likely to report leakage in late pregnancy and up to six months after birth. 
Finally, our last set of main findings are about treatment. For pregnant women who started pelvic floor muscle exercises because they already had urine leakage, the evidence is particularly weak and it’s not clear whether the exercises reduced leakage in late pregnancy or in the year following childbirth. It’s also not clear if leakage was reduced in the year after childbirth if women began the exercises after having their baby.

Stephanie: In summary, offering structured pelvic floor muscle exercises to continent women early in pregnancy may have a clinically important effect in preventing urinary incontinence in late pregnancy and postpartum. The effects are smaller, but still important, when a mixed prevention and treatment approach is taken but there is uncertainty about the effects as a treatment for leakage in pregnant and postnatal women. This contrasts with the more established effectiveness of the exercises in mid-life women, and merits further investigation.

John: If you would like to learn about the findings and the exercises, and watch for further updates of the review, just go online and search 'Cochrane and pelvic floor muscle training in pregnancy'.