Crohn's disease, pregnancy, and birth weight

Although there is general agreement that conception should be avoided when Crohn's disease is active, many questions remain unanswered for the woman with Crohn's disease in remission who becomes pregnant.

Sixty-five charts of women with Crohn's disease quiescent at the start of pregnancy were identified between January 1993 and December 1997. Each pregnancy was matched to a healthy control pregnancy by date, age, parity, smoking status, and gestational age +/- 1 wk, and comparisons were carried out using matched analyses.

The two groups were similar in terms of maternal height, weight, and body mass index (BMI), in addition to the matched variables. The incidence of pregnancy complications was similar for most of the complications examined, whereas the incidence of poor maternal weight gain differed significantly between the groups (17/65 vs 2/65, p < 0.001). Flare-up of the Crohn's disease was seen in 13/65 (20%) of pregnancies. The greatest differences in neonatal outcomes were in terms of birth weight (3150+/-80 g vs 3500+/-60 g) and birth weight percentile (36.7%+/-.6% vs 57.5%+/-3.4%). Overall, there were 16 (24.6%) small for gestational age (SGA) births in the Crohn's group, compared with only one (1.5%) in the control group (p = 0.0007). Multivariate analysis was performed to identify factors predictive of SGA births in the Crohn's group. Ileal Crohn's disease was a statistically significant predictor (p = 0.035), whereas previous bowel resection trended toward statistical significance (p = 0.065).

In view of the risk of low birth weight, all women with Crohn's disease who become pregnant should be followed carefully during the pregnancy, particularly those who have ileal disease or who have previously undergone bowel resection. Furthermore, smoking cessation needs to be aggressively pursued in these patients.