Medical therapy and birth outcomes in women with Crohn's disease: what should we tell our patients?

It is not surprising that women with inflammatory bowel disease (IBD) have a greater risk of an adverse pregnancy outcome. Although it is ideal to be in remission during conception and pregnancy, women often flare during this critical time. Paradoxically, while pregnant, women often stop the medications that have worked so well to maintain remission due to the fear that these drugs may harm the fetus. Many women with IBD find it especially difficult to continue 6-mercaptopurine (6-MP) and azathioprine (AZA) during pregnancy. There have been a number of studies of IBD and pregnancy but none have successfully separated out the effects of disease activity and drug therapy on pregnancy outcomes. The study by Norgard et al. in this issue of the American Journal of Gastroenterology is the first to combine the power of two national data registries of hospitalizations, outpatient visits, and births with a national prescription database. The authors have detailed information on 900 babies born to mothers with Crohn's disease as well as information on every IBD drug prescribed during pregnancy from 1996 to 2004. The worrisome results here are the greater risk of preterm birth and congenital abnormalities among patients prescribed AZA/6-MP throughout their pregnancies. However, although the authors have accurate information on drug exposure during pregnancy, their measures of disease activity cannot be as accurate due to the nature of this database study. Only a prospective pregnancy registry of IBD patients can adequately differentiate the effects of disease activity and medication use on adverse pregnancy outcomes.