This is the conclusion of new research from the Sahlgrenska Academy at the University of Gothenburg in Sweden. You can read the full release at ScienceDaily, but in brief, there were 6,000 women involved in the research, all of whom had babies between 1985 and 1988.
"Overall, the prevalence of UI was considerably higher after a vaginal delivery (40.3%) compared to women who delivered by caesarean section (28.8%). The study also found that the prevalence of UI for more than 10 years almost tripled after VD (10.1%) compared to women who had a CS (3.9%)."
The authors also note that the risk of UI in obese women more than doubled in comparison to women with a normal BMI after VD and more than tripled after CS.