It’s no secret that the United States lags the rest of the developed world when it comes to policies that support mothers and families. As former President Barack Obama put it in 2014: “Family leave. Child care. Flexibility. These aren’t frills. They’re basic needs. They shouldn’t be bonuses. They should be the bottom line.”

Five years and little progress later , we’re learning more and more about the toll inflexible work cultures have on new and expectant mothers.

Last fall, a New York Times investigation exposed the devastating cost of pregnancy discrimination on women in physically demanding jobs. Now, a new study has explored the dangers of a long commute on pregnant women and their unborn babies. The longer the commute, the study found, the worse the impact.

The study, recently published by researchers at the University of Wisconsin-Madison and Lehigh University, suggests that women who travel 50 or more miles each way to work by car may be at a “much greater risk” of having low-birth-weight babies (under 5.5 pounds) as well as fetuses with intrauterine growth restriction — a condition, in which the fetus doesn’t grow as fast as expected, that’s generally associated with mothers who have diabetes, high blood pressure, malnutrition or infections including syphilis.

Worse, for every 10 miles of travel distance added to a long commute, the probability of low birth weight goes up by 0.9 percentage points and the probability of intrauterine growth restriction rises by 0.6 percentage points, according to the study, which looked at pregnant women in New Jersey (a state with some of the longest commute times in the nation) .