Inflammatory bowel disease roughly doubles the chances of pregnancy complications, reveals research published ahead of print in Gut.
Inflammatory bowel disease, or IBD for short, is an umbrella term for the inflammatory disorders of Crohn's disease and ulcerative colitis.
The research team re-analysed 12 studies published over the past 20 years, which assessed the impact of IBD on pregnancy and birth.
In all, the dozen studies, drawn from an extensive search of published material, involved almost 4000 women with IBD and more than 320, 000 people without the condition, with whom they were compared.
Around two thirds of the women had Crohn's disease; the remainder had ulcerative colitis.
The results showed that women with IBD were almost twice as likely to have a child born prematurely, and more than twice as likely to have a child born below normal weight.
Premature and low birthweight babies run the risk of developmental problems and a greater likelihood of serious chronic illness.
Women with IBD were 1.5 times as likely to have had a caesarean section as their healthy peers, especially those with Crohn's disease.
And the rate of congenital birth defects in babies born to mothers with IBD was more than twice as high.
If a woman becomes pregnant during an active bout of disease the risks of pregnancy complications are likely to be greater, suggest the authors.