Maternal Risk Factors and Perinatal Characteristics in Congenital Diaphragmatic Hernia: A Nationwide Population-Based Study

Background: The etiology of congenital diaphragmatic hernia (CDH) remains poorly understood. We hypothesize that environmental factors play an important role in the development of CDH. Aim: The objective of this study was to investigate associated maternal risk factors in pregnancies with CDH. Material and Methods: The study was a nationwide, population-based prospective case-control study consisting of a cohort of newborn children entered into the records of pregnant women receiving antenatal care in Sweden, registered in the Medical Birth Registry during the period from January 1, 1982 to December 31, 2015. The study outcome CDH and the different exposures were assessed through linkage to the Swedish National Patient Registry for both cases and mothers. Results: A total of 972 cases of CDH were registered into one of the national registries in Sweden between 1982 and 2015. The incidence of neonates with CDH in Sweden from 1982 to 2015 was 3/10,000 live births. The mortality rate during the study period was 31%. Maternal age, ethnicity, parity, exposure to tobacco, BMI, IVF, previous history of spontaneous abortion or intrauterine fetal demise, and coexisting chronic diseases (urinary tract infection, chronic renal disease, pregestational diabetes, epilepsy, asthma, ulcerative colitis, inflammatory bowel disease, or systemic lupus erythematous) were not associated with an increased risk of CDH in the fetus. There was a significant association between maternal hypertension and the risk of the child being affected by CDH (OR 3.32, 95% CI 1.41-7.79, p = 0.01). No association was found between preeclampsia and CDH. Conclusions: Pregestational hypertension is associated with an increased risk of giving birth to a baby with CDH, but no association was observed in pregnancies developing preeclampsia and the occurrence of CDH.