Objective: Our study aimed to compare the birth outcomes in offspring of women with ulcerative colitis with controls without the disease.
Methods: A cohort study of 1531 newborns to mothers with ulcerative colitis, and 9092 controls, based on linkage between the Danish National Registry of Patients and the Danish Birth Registry from 1982 to 1992.
Results: Among the births to women with ulcerative colitis, 569 took place before and 962 after the first hospitalization for ulcerative colitis. We found no increased risk of either low birth weight or intrauterine growth retardation for newborns born before or after the mothers' first hospitalization. The risk of preterm birth was increased when birth occurred after the mothers' first hospitalization (odds ratio = 1.4, 95% confidence interval = 1.1-1.9), and particularly when the first hospitalization for ulcerative colitis took place during pregnancy (odds ratio = 3.4, 95% confidence interval = 1.8-6.4).
Conclusions: In the offspring of women with ulcerative colitis, we found no increased risk of low birth weight or signs of intrauterine growth retardation. The risk of preterm birth was increased in the offspring of women with ulcerative colitis, particularly when the first hospitalization for ulcerative colitis occurred during pregnancy.