The physical disruption of Hurricane Sandy is overwhelming, but it can be measured: tens of billions of dollars in damage, lost income, and interrupted business. Catastrophes and their ensuing stress also take a toll on relationships and interrupt our best-laid plans. The human costs are harder to measure, but we can predict some of Sandy’s likely impact by examining the effects of disasters on marriage, divorce, and birth.

Next year, expect to see a rise in the number of marriages in the areas hit by Sandy. Hurricane Hugo hit South Carolina in 1989 at a time when the marriage rate in South Carolina was declining. In their examination of the social consequences of Hugo, Catherine Cohan and Steve Cole found an upward hitch: The marriage rate increased by 0.7 per 1,000 people in 1990 before returning to the pre-storm decline. Although the overall effect was small, it was especially pronounced in the seven counties hit hardest by the disaster.

The marriage-rate boost seems fairly intuitive. People seek security in the face of threats and grow closer to their sources of comfort. (The whole field of attachment theory is based on how this phenomenon plays out.) Catastrophes can also give people a push into the next stage of their lives and provide a reality check about what’s important.

Those same bonding mechanisms should make the already coupled more likely to stay together after Sandy, right? After all, one of the least-known legacies of the 9/11 disaster was its impact on divorce: In September 2001, the number of couples filing for divorce in New York dropped by 32 percent. The researchers who analyzed the effects of Hurricane Hugo also examined divorce rates after 9/11 and found that the drop in filings couldn’t be explained by interruptions to civil services. The decrease falls in line with that following other man-made disasters: After the Oklahoma City bombing in 1995, divorce rates decreased for the seven counties around Oklahoma City. Perhaps most surprising was the effect of 9/11 on so-called psychologically similar cities: Philadelphia; Bergen County, N.J.; and Los Angeles also experienced significant declines in divorce filings in September 2001. According to the researchers, couples in those cities could easily imagine themselves experiencing something similar to 9/11.

Hurricane Sandy isn’t likely to leave marriages intact in the same way that 9/11 did, however. While divorce rates decrease after man-made catastrophes, they tend to increase after natural disasters. Hurricane Katrina, for example, devastated marriages. The 2005 divorce rate in Orleans Parish was 2.3 per 1,000 people; a year later, it nearly doubled to 4.4. In Jefferson Parish, the rate increased from 2.9 to 3.9. Unmarried people may have fled in the post-Katrina exodus, leaving behind a disproportionate number of married couples, but this finding has been observed after other natural disasters that didn’t experience such a massive outward migration. The divorce bump in counties hit by Hurricane Hugo was slight by Katrina standards—0.3 additional divorces per 1,000 people—but accounted for a statistically significant increase that year before the rate returned to pre-storm levels in 1991. After Hurricane Andrew hit Florida, Dade County’s divorce rate spiked by 30 percent.

Why would people stick together after a man-made disaster but split up after hurricanes? Think of recent hurricanes as the inverse of 9/11: Instead of a large loss of life and relatively concentrated physical damage, the populations grappled with relatively small loss of life but widespread physical damage. After 9/11, people became acutely aware of death but faced no great increase in the everyday stressors that take a real toll on marriage. In these conditions, couples stayed together.

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 .

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.