Weathering the Storm: Hurricanes and birth outcomes

A growing literature suggests that stressful events in pregnancy can have negative effects on birth
outcomes. Some of the estimates in this literature may be affected by small samples, omitted variables,
endogenous mobility in response to disasters, and errors in the measurement of gestation, as well as
by a mechanical correlation between longer gestation and the probability of having been exposed.
We use millions of individual birth records to examine the effects of exposure to hurricanes during
pregnancy. The data allow us to measure outcomes precisely and to follow the same mother over
time; we also suggest estimation methods that correct for omitted unobserved fixed characteristics
of the mother, endogenous moving in response to storms, and the above mentioned correlation between
gestation length and exposure. We find that exposure to a hurricane during pregnancy increases the
probability of complications of labor and delivery, and of abnormal conditions of the newborn such
as being on a ventilator more than 30 minutes and meconium aspiration syndrome. Although we do
not directly measure stress, our results are supportive of the idea that stressful events in pregnancy
can damage the health of the fetus. However our results suggest that the effects may be subtle and
not readily apparent in terms of widely-used metrics such as birth weight and gestation.