A retrospective controlled study of 98 pregnancies complicated by inflammatory bowel disease was conducted with control pregnancies matched for parity, sex of offspring, year of delivery, and maternal age. Two control pregnancies were paired with each study case. There was no significant difference in weight gain or hemoglobin levels between the two groups. However, patients with inflammatory bowel disease had a statistically significantly higher preterm delivery rate (p less than 0.01) than the rate of the control group. The risk of these two disorders was further increased when exacerbation of the bowel disease occurred during pregnancy.