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Are Pregnancy, Marriage, and Divorce Contagious?

Research reveals the subtle but surprisingly powerful ways friends influence us.

Federico Marsicano/Shutterstock
Source: Federico Marsicano/Shutterstock

The “me” and “you” in a relationship seem like the only ones who can or should be making major decisions for a couple, right? Do you get married? Do you get divorced? Do you have a baby? In the end, it’s just two people weighing the options and deciding.

Or is it?

We might think that our major relationship choices are made exclusively by ourselves and our partners, but recent research underscores the surprisingly potent influence of our social networks.

The reality, it turns out, is even our most serious life and relationship decisions are very much influenced by our friends and families.

Pregnancy May Be Contagious

A recent study by Balbo and Barban (2014) tested whether having friends who become parents affected women’s own likelihood of becoming first-time mothers. (In this case, the authors focused only on planned, rather than unplanned, pregnancies). They examined a nationally-representative sample of 1,726 women in the U.S. whose friendship data and fertility information were gathered multiple times between ages 15 and 30. Two of their findings stand out:

  1. If your friends become parents, you’re more "at risk." The study controlled for potentially influential demographic factors (age, race, socioeconomic status) and even included potential "selection effects" (such as choosing friends who share the same family plans). Their findings suggest that interacting with childbearing friends ups a woman’s likelihood of becoming a first-time parent herself.
  2. Friends’ childbearing influence is short-term. Friends' baby decisions apparently have their strongest influence around two years later after their deliveries; then their influence declines. This is a more delayed influence than that of women's siblings, whose strongest impact on their sisters' potential pregnancies tends to be within the first year of having a first baby.

So it seems that starting a family, considered to be such a personal decision for a couple, may be unconsciously influenced by the experiences of those in their social network.

Are other major relationship decisions also affected by friends’ decisions?

Is There a "Marriage Bug"?

The social influence on a couple's decision to marry, it seems, is much less linked to friends’ decisions (Balbo, Barban, & Mills, 2013). They are, however, subject to social influence. In the case of marriage, individuals’ decisions to marry are influenced by one’s general peer group. The difference between friends and a peer group is a subtle, but important distinction. A peer group is a contextual factor that includes non-friends or acquaintances ; it is not limited to close friends or relatives. In other words, it might be the “year of weddings” in part because many people your age in your area are getting married, rather than because your specific friends are tying the knot. This is also known as the "cohort effect."

Can You "Catch" Divorce?

Choices generally deemed as positive, like marrying or starting a family, are not the only ones subject to social influence. Break-ups are as well. New evidence suggests that divorce can spread through social networks (McDermott, Fowler, & Christakis, 2013).

By analyzing data from the Framingham Heart Study, a well-known, longitudinal health and lifestyle study, a group of researchers discovered that divorce moves in clusters defined by social ties. Friends who divorce affect the likelihood that their friends will divorce; this influence even extends to friends of friends. The authors suggest that there may be value in studying divorce in the same way that we examine epidemics of disease, as the apparent spreading effect of divorce suggests that breaking up may be somewhat less a reflection of a couple’s own issue, and more of a social, or even a public health, concern.


Balbo, N., & Barban, N. (2014). Does fertility behavior spread among friends?. American Sociological Review, 79, 412-431.

Balbo, N., Barban, N., & Mills, M. (2013). Friend and peer effects on entry into marriage and parenthood: A multiprocess approach (No. 056).

McDermott, R., Fowler, J. H., & Christakis, N. A. (2013). Breaking up is hard to do, unless everyone else is doing it too: Social network effects on divorce in a longitudinal sample. Social Forces, 92, 491-519.