By Elise Viebeck - 04/11/13 04:28 PM EDT
Figures show that adults under age 26 who enrolled in a parent's plan in 2011 were nearly four times as likely to use their insurance for pregnancy.
Mental illness and substance abuse, meanwhile, accounted for the plurality (42 percent) of that group's inpatient hospital visits. The comparison group spent the majority of its hospital time being treated for miscellaneous problems.
Under the Affordable Care Act, health plans with dependent coverage must allow young adults to remain insured until they are 26.
Millions of young adults have gained coverage as a result, prompting the uninsured rate among those ages 19 to 25 to dramatically fall over the last several years.
The coverage requirement is popular with consumers. President Obama frequently touted it on the 2012 campaign trail, and insurers have complied.
But EBRI's study found a cost disparity between the young people who enrolled in a parent's plan after 2011 and those who were already receiving that coverage.
The first group spent an average of 15 percent more on healthcare, researchers found, suggesting a higher cost of treatment for conditions like substance abuse and pregnancy compared with a "miscellaneous" hospital visit.
The study did not provide further detail about the first group's mental illness and substance abuse diagnoses.