English summary Background Due to increasing rates of caesarean sections worldwide on the one hand and the decreasing birth rates on the other hand there have been various attempts to identify relations between caesarean sections and subfertility. Our aim was to compare women after caesarean section and natural birth related to the time to a subsequent pregnancy and beeing diagnosed with "infertility" for the first time. Methods Using a retrospective database analysis of the "IMS Disease

more »

... r Database" we included women aged between 16 and 40 years with a childbirth between 2000 and 2013 either by natural birth or caesarean section and had no prior diagnosis of infertility. The data had been collected directly from 227 gynaekologist practices and included information about diagnosis-code based on ICD-10. The main outcomes were first-time diagnosis "Infertility" and "subsequent pregnancy" within 10 years after the first delivery. We used a multivariate cox regression model and adjusted to patient characteristics. The Kaplan-Maier method was used to estimate the cumulative incidence of diagnosis "infertility" as well as time period between first delivery and subsequent pregnancy after caesarean section and natural birth. Results Women after caesarean section were more likely to be diagnosed with "Infertilty", they also had a lower chance for a second pregnancy compared to women after natural birth. Within 10 years from index date of 6483 women in each group 64% after natural birth and 57,9% after caesarean section became pregnant again. The probability of a subsequent pregnancy was also decreased for women with deterioration of the menstrual cycle and polycystic ovary syndrome. During the same period there were 19,5% of the patients after caesarean section diagnosed with "infertility" compared to 18,5% after natural birth. Conclusion This study indicates a slightly increased risk for infertility and a lower chance of a second pregnancy after a caesarean section in Germany. Further investigations will be needed [...]