Did you and your bestie get pregnant around the same time? Or is more than one member of your social circle expecting? There’s long been a theory that women tend to “sync up” when they spend a lot of time together. If you’re not riding the crimson wave at the same time as at least one of your friends, are you even friends? But now, a recent study suggests that periods aren’t the only things women do together. Turns out, pregnancy can be contagious within social circles. When your friend tells you she’s pregnant and you’re not ready to be a mom, maybe take a short hiatus from the group!

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Pregnancy can be contagious among women in close social circles, according to the National Longitudinal Study of Adolescent Health (ADD Health).

Researchers analyzed data on 1720 women who participated in the study, from the mid-1990s to mid-2000s. Using home interviews, they tracked women who were at least 15 years old in 1995, and found that about half of the women had at least one child within the decade. One of the questions they asked was about “friendship ties”, so researchers could have an idea of the patterns among groups of friends as they got older.

They focused on pairs of friends whose relationships began in high school, and continued through the years. That’s where things got interesting.

According to the authors of the study, this is where they found the strongest evidence that pregnancy can be contagious. They say, “We found this effect to be short-term and inverse U-shaped: an individual’s risk of childbearing starts increasing after a friend’s childbearing, reaches a peak around two years later, then decrease.” (LOL forever at risk of childbearing.)

Researchers of this study call this the “fertility influence”, and have some theories that might help explain it: social learning, cost-sharing, and social influence.

In other words, women may get pregnant around the same time as their friends when they see a close friend do it successfully, when there may be financial perks to having kids at the same time (think child-care cost sharing), and so they don’t feel “left behind” as their friends enter parenthood.

It’s a really interesting theory that makes a lot of sense. Did you and your friends have babies around the same time for any of these reasons?

(Image: iStock / vadimguzhva)