Congenital Abnormalities and Other Birth Outcomes in Children Born to Women with Ulcerative Colitis in Denmark and Sweden

Background: Studies of women with ulcerative colitis (UC) during pregnancy have reported increased risks of preterm delivery, growth restriction, and congenital malformation. However, the results are inconsistent due to inadequate study design and limitations in sample size. Methods: We performed a population-based prevalence study on 2637 primiparous women with a UC hospital diagnosis prior to delivery and 868,942 primiparous women with no UC diagnosis in Denmark and Sweden, 1994-2006. Logistic regression analysis was used to estimate relative risks for moderately (32-36 weeks) and very (before 32 weeks) preterm birth, 5-minute Apgar score < 7, small-for-gestational-age (SGA) birth, stillbirth, neonatal death, and congenital abnormalities. Results: Maternal UC was associated with increased risk of moderately preterm birth (prevalence odds ratio [POR] 1.77, 95% confidence interval [CI]: 1.54-2.05), very preterm birth (POR 1.41, 95% CI: 1.02-1.96), cesarean section (POR 2.01, 95% CI: 1.84-2.19), and neonatal death (POR 1.93, 95% CI: 1.04-3.60). The strcngest associations were observed for prelabor cesarean section (POR = 2.78, 95% CI: 2.38-3.25) and induced preterm delivery (POR 2.55, 95% CI: 1.95-3.33). There was a slightly Increased risk of SGA birth (POR 1.27, 95% CI: 1.05-1.54). We found no association between UC and overall risk of congenital abnormalities (POR 1.05, 95% CI: 0.84-1.31) or specific congenital abnormalities. Risks for adverse birth outcomes were higher in women with previous UC-related surgery and hospital admissions. Conclusions: Women with UC have increased risks of preterm delivery, SGA-birth, neonatal death, and cesarean section but not congenital abnormalities. Adverse birth outcomes appeared correlated with UC disease severity.