Mothers-to-be who are obese during the first trimester of pregnancy are more likely than normal-weight women to have an infant with a cleft lip or cleft palate, according to a study in Sweden.

Drs. Marie Cedergren and Bengt Kallen analyzed data from Swedish medical health registries that listed maternal height and weight in early pregnancy and the presence of birth defects in offspring. Their study compared 1422 women who had infants with orofacial clefts with all women -- nearly a million -- who delivered between 1992 and 2001.

The researchers found that being obese was associated with a 30 percent increased risk for having an infant with an orofacial cleft, compared with being normal weight.

Cedergren, from Linkoping University, and Kallen, from the University of Lund, note in their report in the Cleft Palate-Craniofacial Journal that the increased risks for orofacial cleft among obese women are on a par with those linking obesity with neural tube defects and congenital cardiovascular malformations.

They estimate that maternal obesity accounts for 23 percent of all cases of cleft lip and cleft palate among children of obese mothers. The duo suggests that undetected type 2 diabetes or improper nutrition could be responsible for the increased risk of orofacial clefts.

"The knowledge about various negative reproductive effects of prepregnancy obesity could perhaps contribute to behavioral changes concerning nutrition and physical exercise among women of fertile age," the researchers write.

SOURCE: Cleft Palate-Craniofacial Journal, July 2005.