If you’re a mom and if you were pregnant at the same time as another friend or co-worker, you may have heard people joke that “there’s something in the water,” basically joking that pregnancy is something you can “catch.”

While we won’t go into the birds and the bees, we know that you can’t exactly “catch” pregnancy like you catch a cold, but it does seem that there are times when multiple women in the same circle (whether at work or a group of friends) are pregnant at the same time. This phenomenon is so common that scientists have actually researched it.

A new study published by The American Sociological Association journal sheds some light on just why pregnancy not only appears to be but actually kind of IS contagious.

In the study, researchers surveyed 1,720 women from the 1990s into the 2000s. Over half of the women who participated became pregnant before the study was over.

One big reason the study found for pregnancy being “contagious” has to do with “friendship ties.” Basically, that means that women want to do what their friends are doing, and this goes beyond dressing similarly and listening to the same music. When women are friends before they have children and then their friends start having children, they’re more likely to start having children too.

According to the study, “individuals adapt their behavior to match others they consider to be in similar social positions or with whom they share characteristics.”

This doesn’t exactly mean that women are getting pregnant just because they want to be like their friends, but it does mean that women are more likely to have children if they think that it’s the right thing to do based on what they see people around them doing. According to the study, “Individuals who have several friends with children may thus be more likely to have a child, too.”

Another consideration is that when women see their friends raising children, they have the tendency to think, if she can do it, I can do it too. This also accounts for why friends may have a similar number of children. When you see your friend successfully raising multiple children, you’re more likely to feel like you can successfully raise multiple children too.

There is also an aspect where women have children because they don’t want to be “left out.” When you become a parent, your whole life changes including how and when you have time to socialize. When you have children at the same time as your friends, your social interaction changes at the same time as your friends’, which can seem easier. Instead of late nights out with your gal pals, you meet them at the park for a playdate.

What do you think about this study? Did you have children around the same time as your friends?