Crohn's disease can have negative implications in pregnancy, including increased risks for preterm delivery and low birth weight, in women with active disease at conception. Smoking increases these risks and can exacerbate Crohn's disease symptoms. Crohn's disease status was evaluated in 70 pregnancies among 61 women, and the results of the study were reported in Alimentary Pharmacology and Therapeutics (March 2005). The Harvey-Bradshaw index (HBI) of disease status was determined during the year before conception, during the 9 months of gestation, and during the year after delivery.
Of the participants, 22 of the pregnancies involved mothers who smoked. Thirteen mothers significantly curtailed smoking during gestation but resumed after delivery, 3 quit smoking altogether, and 6 continued to smoke throughout pregnancy and after delivery. There was no significant change in average HBI score among the nonsmokers. In the 22 pregnancies involving smokers, average HBI scores were significantly improved during gestation, compared with scores before conception and after delivery. The authors concluded that reduced smoking during pregnancy has a positive effect on Crohn's disease symptoms and, thus, will improve pregnancy outcomes in mothers with the disease.