Long commutes to work during pregnancy and infant health at birth.

We conduct the first empirical study to examine the health impact of long commutes to work during pregnancy on fetuses and infants at birth, using unique data that contain information on not only a woman's home address but also her employer's address during pregnancy, which allows us to calculate the maternal travel distance during pregnancy. Our study contributes to the literature on the relationship between maternal stress during pregnancy and adverse birth outcomes by focusing on the understudied chronic stress induced by long commutes, rather than the stress triggered by a one-time significant event, such as a natural disaster. We find that among long-distance commuters, increasing the maternal travel distance during pregnancy by 10 miles is associated with increases in the probabilities of low birth weight and intrauterine growth restriction by 0.9 and 0.6 percentage points, respectively. In addition to the maternal stress induced by long commutes being one potential biological mechanism, we find suggestive evidence showing that maternal long commutes during pregnancy are also associated with under-utilization of prenatal care.