To Örebro University

Introduction: The influence of pregnancy on the risk of ventral hernia recurrence is not known. This study aims to assess whether the frequency of pregnancies is associated with an elevated risk of developing ventral hernias.

Method: This nationwide study cohort constitutes women borne 1950 – who were registered in the Swedish Birth Register (MBR). Data on pregnancies, distinguishing between vaginal and caesarian sections, were retrieved from the Birth Register. The cohort was cross-matched with the National Patient Register (NPR) to identify subsequent primary hernia repairs.

Results: A total of 1,630,754 women born between 1950 and 1980 were        included in the study. Among them, 1,588,609 (92.3%) were registered for at least one birth. The incidence rate for Umbilical Hernia Repair (UHR) and Epigastric Hernia Repair (EHR) was 13.21 per 100,000 person-years and 5.4 per 100,000 person-years, respectively. When compared with women registered for one delivery, the incidence rate ratio for UHR was 1.3 (95% CI: 1.26–1.33, P < 0.001) among thos eregistered for two deliveries and 1.6 (95% CI: 1.58–1.68, P < 0.001) among those registered for ≥3 deliveries.

The incidence rate ratios were 1.29 (95% CI: 1.20–1.39, P < 0.001) and 1.34 (95% CI: 1.24–1.45, P < 0.001) for EHR among women with two and ≥3 registered deliveries, respectively.

Conclusion: A history of more than one pregnancy is associated with an increased incidence of umbilical and epigastric hernias.