Birth Outcomes in Women with Inflammatory Bowel Disease: Effects of Disease Activity and Drug Exposure

Background: Ulcerative colitis (UC) and Crohn's disease (CD) have been associated with increased risks of adverse birth outcomes. Disease activity and drug exposure may contribute to the association. Methods: A cohort from the Swedish health registers including 470,110 singleton births in Sweden from July 2006 to December 2010; 1833 to women with UC and 1220 to women with CD. Birth outcomes for women with UC and CD were compared with outcomes among those without disease. Diseased women were categorized by drug exposure, need of surgery, and hospital admissions as (1) no disease activity and (2) stable or (3) flaring disease. Logistic regression was used to calculate odds ratios with adjustments (aOR) for maternal age, parity, smoking status, body mass index, and comorbidity. Results: There were increased risks of preterm birth for both UC (aOR, 1.78; 95% confidence interval [CI], 1.49-2.13) and CD (aOR, 1.65; 95% CI, 1.33-2.06). Risks were more pronounced in women with flaring disease during pregnancy. Risks of small for gestational age, low Apgar score, and hypoglycemia were also increased. The risk of stillbirth was elevated in women with CD, particularly among those with flaring disease (aOR, 4.48; 95% CI, 1.67-11.90). Thiopurine exposure increased risks for preterm birth, both in women with stable (aOR, 2.41; 95% CI, 1.05-5.51) and with flaring disease (aOR, 4.90; 95% CI, 2.76-8.69). Conclusions: Women with UC and CD are at increased risk of adverse birth outcomes, such as stillbirth, growth restriction, and preterm birth, particularly when they suffer from flares throughout pregnancy. Thiopurine exposure seems to further increase risks, independently of disease activity.