After you, your friends and your colleagues reach a certain age threshold (which will vary depending on location, lifestyle and other related factors), you’ll likely notice an interesting phenomenon: Everyone suddenly seems to get pregnant at the same time.
Whether it’s a deluge of baby shower invites from within your social circle or numerous simultaneous maternity-leave requests from your coworkers, these signifiers reflect an intriguing scientific principle, recently proven by the National Longitudinal Study of Adolescent Health (aka Add Health). You’re not imagining things. To a certain extent, pregnancy actually is contagious.
Scientists performed a survey of 1,720 women from the mid 1990s to the late 2000s, honing in on pairs of high school friends who remained close into adulthood. By analyzing data, the researchers discovered a direct (yet unsustained) “contagion” link between these women and their respective planned pregnancies.
“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,” explained the research team. Add Health coined a phrase to explain this effect: the “fertility influence.”
The researchers attribute the fertility influence to three factors: social learning (the idea that women will feel a stronger draw to motherhood once they see a friend handling it well), social influence (women may get a sense of FOMO from their reproducing pals) and cost-sharing (if a friend has a baby shortly before you, you’ll be able to benefit from her help with childcare, supply-borrowing and activity-planning).
Researchers spotted a direct correlation between the closeness of a friendship and its likelihood of affecting pregnancy decisions, indicating that while you may become subconsciously influenced by your work wife’s choice to get preggers, random Karen in accounting’s happy announcement won’t do much to sway you. Also, the test revealed that the contagion spread by the fertility influence doesn’t impact sibling relationships. However, researchers found an explanation for this gap, suggesting that “in today’s individualized societies, [chosen] friends may be equally or more important than siblings and other family members.”
In conclusion, your “everyone is having a baby right now!” feeling isn’t based on paranoia — there actually is a form of “contagion” at play here.
This article originally appeared on Fairygodboss. As the largest career community for women, Fairygodboss provides millions of women with career connections, community advice and hard-to-find intel about how companies treat women.