Why Terrorist Attacks Are Good for Marriage but Hurricanes Are Bad

Health and medicine explained.
Nov. 5 2012 6:35 PM

Will Sandy Bring a Baby Boom or Baby Bust?

How disasters change marriage, divorce, and birth rates.

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In the immediate aftermath of Sandy, people are dealing with significant interruptions to every aspect of their daily routines, hefty economic stressors, and increased risk of anxiety and depression, all of which are known to bring relationships to breaking points.

Families suffer in other ways as well. For women who are already two to three months pregnant, exposure to stressors from Sandy may put them at risk for giving birth to very low-weight babies. Child abuse and domestic violence also tend to increase in the year following a hurricane.

Hurricanes can lead to an increase in dolphins, but what about humans? Birth rates are the source of the biggest disagreement among researchers studying the aftereffects of disasters. Plenty of individual stories suggest a boom: Nine months after Cyclone Yasi hit Australia in February 2011, one hospital reported 120 births instead of its usual 70-80. The idea of a post-disaster baby boom is almost a cliché, and it makes for great copy nine months after disasters .

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Because post-disaster baby booms are vivid, tantalizing stories for newspapers grasping for silver linings, it’s likely that they’re overreported. They’re also prone to selection bias: How many times, nine months after a natural disaster, does a non-baby-boom make the news?

Post-hurricane birth rates in aggregate tell a different story. A study from 2010 (pdf) offers a more complete look at the phenomenon. After examining Atlantic and Gulf Coast storm advisory data from 1995-2001 and birth rates by county, researchers found an explanation for the apparent discrepancy. For every day that a county deals with a mild advisory, such as a tropical storm watch, the birth rate increases by 2 percent nine months later. But the most severe possible notice, a hurricane warning, is correlated with a 2 percent decrease in births nine months later. In the case of Sandy, because the impacted areas faced two days of severe warnings, the study’s lead author estimates that in nine months, the region’s birth rate could decrease by 4 percent.

Intuitively, this makes sense: Heightened stress negatively impacts fertility, starting with sperm motility. But it’s complicated. Increased economic stressors, disruptions to social support and medical care, and post-disaster migration could all affect the birth rate. (New Latino immigrants to the New Orleans area post-Katrina, for example, may help account for a baby boom after the storm.) Being reminded of one’s own mortality is said to increase people’s desire for children.

It’s impossible to calculate the sum of these effects of Sandy, but at least we can prepare for learning one lesson all over again: No matter how carefully we plot out the next few decades of our lives, the whims of nature can always gain the upper hand.

Karla Starr is working on a book about the science of luck and chance. She can be found on Twitter at @karlastarr.

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