Do Hurricanes Really Induce Labor?

Oh, the tales a labor and delivery nurse can tell.

Along with the general chaos that can accompany new babies on their way into the world, all it takes is a full moon or—more dramatically—a raging hurricane to make things really interesting. That’s the conventional wisdom, anyway, among those who swear that pregnant women go into labor, en masse, during major storms.

But is it true?

With Hurricane Matthew expected to deliver a devastating blow to Florida, pregnant women are already heading to the hospital ahead of time as a precaution. Two hospitals in the Miami area are allowing some pregnant women to register for sheltering at the hospital before the storm hits, according to the local ABC affiliate there. Priority will likely be given to women who are pregnant with twins or multiples, and who are at least 34 weeks pregnant—along with other pregnant women who have been diagnosed with placental abnormalities or have a history of preterm labor.

When Hurricane Andrew hit Florida in 1992, some 1,500 pregnant women flocked to area hospitals. “I’ve never seen so many pregnant people in my entire life,” a spokeswoman for Memorial Hospital, in Fort Lauderdale, told The Sun Sentinel at the time. Some women ended up delivering their babies over the course of the hurricane—though most did not.

Still, there is evidence to support the idea that more women deliver babies at low barometric pressure—one of the key atmospheric conditions associated with a hurricane. In a 2007 paper published in the Archives of Gynecology and Obstetrics, researchers found “a significant increase” in pregnant women whose water broke—signaling delivery is imminent—during low pressure systems. The researchers concluded that low barometric pressure indeed induces delivery.

Additional studies have found similar outcomes, including a 1985 study that counted a “significant increase” among women whose water broke prematurely within three hours of an atmospheric pressure drop. Other meteorologic conditions seem to affect pregnancy outcomes, too. In desert climates, according to one study, the risk of preterm birth is higher in the spring and autumn, when the weather is most unstable.

There’s also a growing body of medical literature that finds links between stressful events in pregnancy—including natural disasters—and poor birth outcomes. One 2013 study, found that even if a hurricane doesn’t induce labor, exposure to a hurricane during pregnancy increases a baby’s likelihood of some abnormal conditions—like needing to go on a ventilator for more than 30 minutes after delivery. Other studies have found less decisive links—or no links at all—between hurricanes and the onset of labor, and many scientists agree the relationship between labor and hurricanes requires more study. Most women, even those who are approaching their due date, won’t deliver their babies just because a hurricane is approaching.

Yet severe storms, generally, present all kinds of potential logistical problems to expectant moms. In 2013, a Connecticut woman’s husband pulled her, via sled, so she could make it to the hospital amid heavy snow and road closures.

“In principle, hurricanes could also subject pregnant women to other negative conditions including injury, disruptions in the supply of clean water, inadequate access to safe food, exposure to environmental toxins, interruption of healthcare, or crowded conditions in shelters...” wrote Janet Currie, the author of the 2013 study, published in the Journal of Health Economics. “The primary threat to pregnant women in the path of a hurricane is the stress that is generated by the fear of the hurricane, as well as by the property damage and disruption that follows it.”