Pregnant women who are in a car crash are much less likely to lose the fetus or have complications if they are wearing a seat belt, according to a study published Wednesday.

Researchers found that among 57 pregnant women who were in a crash, those wearing a seat belt were 84 percent less likely to lose the fetus or suffer a major complication like preterm delivery.

The findings, reported in the American Journal of Obstetrics & Gynecology, counter the notion that seat belts are a bad idea during pregnancy.

Some pregnant women worry that the lap belt, which runs across the lower abdomen, could end up doing harm if they were to have a car crash, explained senior researcher Dr. Mark D. Pearlman, vice-chair of obstetrics and gynecology at the University of Michigan in Ann Arbor.

But this study clearly shows that pregnant women should buckle up every time they are in a car, he told Reuters Health.

“We have a cost-free intervention that could save a lot of lives,” Pearlman said.

It’s estimated that car crashes cause about 370 fetal deaths each year in the U.S. The new findings suggest that about 200 of those deaths could be prevented if pregnant women always buckled up, Pearlman said.

The findings are based on 57 car accidents involving women who were at least 20 weeks into pregnancy. In each case, a crash investigation team inspected the cars to assess the severity of the crash.

The researchers found that among women who were not wearing a seat belt at the time of the crash, 80 percent either lost the fetus or had major complications such as delivery before the 32nd week, uterine rupture or detachment of the placenta from the uterine wall.

In contrast, of the 41 women who were properly buckled up, 29 percent suffered a fetal death or complication.

Pearlman said that in a 20-mile-per-hour crash, women who were properly belted had a 12 percent chance of a fetal death or complication. The likelihood was 70 percent among women who were unbelted.

According to Pearlman, pregnant women should be sure to use both the lap and shoulder straps of the seat belt, wearing the lap belt below the navel, as low as is comfortable. In cases where the seat belt no longer fits, he noted, women can get a belt extension that will allow them to be comfortably strapped in.

SOURCE: American Journal of Obstetrics & Gynecology 2008.