New study reveals the possible dangers of long commutes during pregnancy

From what to eat to how to exercise to what position in which to sleep, there's a lot for pregnant women to think about. Thanks to a new study, now they can add commutes to that list.

The longer the commute for a pregnant woman, the worse outcomes her child may face, according to a study published last month by researchers at the University of Wisconsin-Madison and Lehigh University.

Women who travel at least 100 miles roundtrip between their homes and workplaces were found to be at "much greater risks" of having low birth weight babies and fetuses with intrauterine growth restriction.

Increasing the distance a woman commutes during pregnancy by 10 miles raises the probability of low birth weight by .9% and the probability of intrauterine growth restriction by .6%, the study found.

Long commutes, defined by the Census Bureau as 50 miles or more to work, during pregnancy are also linked to the "under-utilization of prenatal care" and increased maternal stress, according to the study -- so think missed doctors' appointments and delayed treatments.

Among the women studied, 15% with longer commutes skipped their first pre-natal checkup and were more likely to have their first pre-natal visit very late in their pregnancy -- as late as their third trimester.

The study, which looked at pregnant women in New Jersey, also found long commutes increase stress in pregnant women.

High stress in pregnancy is associated with poor fetal outcomes, like the low birth weight and intrauterine growth restriction also found in the study.

Male fetuses are at higher risk than female fetuses when it comes to pregnancy stress, a fact that has been known for quite some time. A mother's maternal stress can also increase their children's risk of mental health issues later in life, possibly more in female kids, recent research has found, because it, in a sense, hard-wires the stress system.

A long commute is a necessity of life for many working moms, but there are things they can do to lessen the burden of it, experts say.

Dr. Joanna Stone, director of maternal fetal medicine at Mt. Sinai Hospital in New York City, recommends women make sure the commuting option they're using, whether train or car or bus or boat, is the least stressful option possible.

Meditation methods can also be helpful for pregnant women to use to de-stress during their commute, according to Stone.

Finally, Stone advises pregnant women, even in difficult circumstances, take the time they need, whether it's asking to work from home, if possible, or making other parts of their lives at home less stressful.

"You need to take some time for yourself," she said.

In terms of lessening the burden for pregnant women, the study's authors wrote that they believe their research has "important implications" for maternity leave.

"Our study has important implications for public policy proposals that consider expanding maternity leave to cover the prenatal period, which is particularly relevant in the context of the United States," the authors wrote. "Even today, compared with other high-income industrialized countries, the United States is ranked last on every measure of family-friendly policies."

The U.S. is the only advanced industrialized nation without a guarantee of paid leave for new parents, according to the Organization for Economic Cooperation and Development.

Navjot Kaur Sobti, an internal medicine resident physician at Dartmouth-Hitchcock-Medical Center/Dartmouth School of Medicine and a member of the ABC News Medical Unit, contributed to this report.