Pregnant women with multiple sclerosis are at slightly higher risk for some pregnancy complications but are no more likely to have other problems compared with other women, a new U.S. study suggests.

Researchers used a national database on 18.8 million deliveries in the U.S. between 2003 and 2006 to compare newborns born to women with MS and 10,000 other women.

Women with MS were slightly more likely to have caesarean deliveries (42 per cent) compared with 33 per cent in the general population, Dr. Eliza Chakravarty of Stanford University School of Medicine and her colleagues reported in Wednesday's online issue of the journal Neurology.

"These results are reassuring for women with MS," Chakravarty said in release.

"Women and their doctors have been uncertain about the effect of MS on pregnancy, and some women have chosen to delay or even avoid pregnancy due to the uncertainty. We found that women with MS did not have an increased risk of most pregnancy complications."

Women with MS were more likely than women without chronic medical conditions (2.7 per cent compared with 1.9 per cent) to have a fetus with intrauterine growth restriction — a weight less than the tenth percentile for the gestational age, as measured by ultrasound.

'Critical information'

The team also looked at information on 4,730 pregnant women with epilepsy and 187,239 with diabetes — two other disorders associated with higher risks of certain pregnancy complications.

Overall, women with epilepsy had 1.5 times the rate of C-sections.

Pregestatational diabetes mellitus was associated with an increased risk of all adverse outcomes, the team reported.

"Despite significant advances in management of these chronic diseases, many patients and physicians remain uncertain of the potential risks associated with pregnancy and delivery," the researchers wrote. "Our results demonstrate that pregnancy outcomes for women with MS are generally reassuring."

In an editorial accompanying the study, Dr. Gary Franklin of the University of Washington, and Helen Tremlett of the University of British Columbia welcomed the research, calling it "critical information" for doctors and women who are pregnant or those with MS and epilepsy who are considering pregnancy.