That’s likely due, at least in part, to pre-term birth being associated with being more often withdrawn and shy, socially excluded and less willing to take risks in adolescence, says a team from the UK’s University of Warwick. 

As such, they add, more needs to be done in schools and by parents to encourage social interactions when young.

Their meta-analysis of data from up to 4.4 million adult participants shows that those born preterm (before 37 weeks’ gestations) are 28% less likely to be in a romantic relationship, 22% less likely to become parents, and 2.3 times less likely to ever have a sexual partner.

The situation appears even worse for those born very (<32 weeks) or extremely preterm (<28 weeks). Those in the latter category are 3.2 times less likely to ever having sexual relations, for example.

On the upside, the meta-analysis suggests the where adults born pre-terms do have friends or partners, the quality of those relationships is at least as good as for full-term adults.

“The finding that adults who were born pre-term are less likely to have a partner, to have sex and become parents does not appear to be explained by a higher rate of disability,” says lead researcher Marina Goulart de Mendonça, from Warwick’s Department of Psychology. 

“Rather pre-term born children have been previously found to have poorer social interactions in childhood that make it harder for them to master social transitions such as finding a partner, which in turn is proven to boost your wellbeing.”

The study’s findings are published in the journal JAMA Network Open.