Babies who are born prematurely may grow up to be introverted adults, research indicates.

Several studies, including one published this week in the New England Journal of Medicine and two studies published in the July issue of the journal Pediatrics, found that babies born early, even those without physical problems, are more likely to have problems socializing, including shyness, and taking risks, USA Today reported.

The New England Journal of Medicine study, which looked at one million Norwegians ages 20 to 36, found that the earlier babies are born, the less likely they are to marry, have children and earn high salaries.

In two studies of people in their 20s published in Pediatrics, researchers found that former preemies were less likely to leave home, live with a romantic partner or be sexually active, the journal reported.

Click here for more on this story from USA Today.

Click here for the New England Journal of Medicine study.

Click here for the studies reported in Pediatrics.