Many factors can lead to age differences in sex partners, with girls usually dating those older than boys and young men, the study found. Age and number of work hours matter in adolescents, but any negative impact isn't apparent after age 18 or 19, the study found.

The study found that a youth's self-esteem and alcohol use also play a role in the age difference between sex partners, adds Bauermeister.

Bauermeister says the result shows that overall, teenagers who work part-time benefit in almost all areas over those who don't have jobs. However, those benefits come with caveats, he says, according to a university release.

High self-esteem and low use of alcohol offset the negative effects of working too many hours, he said. Those factors also protect youths overall from engaging in riskier sexual behaviour.