Maternal inflammatory bowel disease and offspring body size: a prospective cohort study.

Background: Maternal inflammatory bowel disease (IBD) may influence intrauterine growth and hence size at birth, but the consequences for offspring in later life remain uncertain. This study investigated the growth of children of mothers with Crohn's disease (CD) or ulcerative colitis (UC).

Methods: The Danish National Birth Cohort, comprising 40,640 mother-child pairs with 7-year follow-up of children's height and weight, were linked to the Danish National Disease Register, whereby 50 mothers with CD and 147 mothers with UC were identified. Associations were tested by regression analyses, taking several covariates into account.

Results: Children of mothers with IBD were significantly shorter at birth than children of unaffected mothers (adjusted; CD, difference in cm, -0.82; 95% confidence interval [CI], -1.39 to -0.25; UC, -0.41; 95% CI, -0.75 to -0.07) and they tended to be of lower birth weight (adjusted; CD, difference in grams, -119.7; 95% CI, -246.7 to 7.3; UC, -64.0; 95% CI, -138.7 to 10.7). However, during the first year of life children of IBD mothers reached similar body sizes as children of unaffected mothers. At the 7-year follow-up, girls, but not boys, of CD mothers tended to be overweight (adjusted odds ratio [OR], 2.47; 95% CI, 0.98-6.24) and had increased waist circumference (adjusted difference in cm, 3.48; 95% CI, 1.40-5.58) compared to the unaffected population.

Conclusions: The present study confirms that maternal history of IBD leads to decreased birth size in offspring. Reassuringly, body size in children of IBD mothers approached body size in children of unaffected mothers during childhood.