Universal pre-K is good for both parents and kids.Fly View Productions/Getty ImagesA new study suggests universal pre-K programs could increase parents' earnings.Researchers found that those who enrolled their kids in free pre-K made about 21% moreUniversal pre-K programs have also been shown to help kids' long-term futures.Universal pre-K has long been thought to boost children's lives and futures, but a new study suggests parents could also reap the benefits of free and early education for their kids.Economists found that parents who had the opportunity to enroll their children in a universal pre-K program in Connecticut saw increased earnings by about 21% while their kids were in the program, as well as persistent gains for up to six years after.The study, published in the National Bureau of Economic Research this month, looked at a New Haven pre-K program that provides six and a half hours of free schooling each day to three and four-year-olds, as well as wraparound childcare before and after school.Parents who were lucky enough to win the school lottery saw several positive economic benefits, according to researchers.