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Study: Children rely on Medicaid, but many face coverage gaps

The majority of U.S. children enroll in Medicaid or CHIP during childhood, but many won't stay covered for 18 years, indicating worsening coverage gaps under the Big Beautiful Bill.

Jacqueline LaPointe
By
Published: 01 Oct 2025

Most U.S. children are covered by either Medicaid or the Children's Health Insurance Program by the time they are 18 years old; however, coverage gaps during their childhood are persistent, according to a new study in JAMA.

The findings spell trouble for children who need Medicaid or the Children's Health Insurance Program, also known as CHIP, as the Trump administration implements sweeping Medicaid reforms that will cut $1 trillion from the program's budget and leave an estimated 10 million uninsured by 2030.

"Our study provides a valuable baseline for understanding the extent to which U.S. children's long-term insurance coverage may be affected by these sweeping changes," the study's corresponding author, Ye Shen, a student in the Harvard PhD Program in Health Policy, said in a statement.

Children rely on Medicaid for coverage, CHIP

Three in five U.S. children have enrolled in Medicaid or CHIP by age 18, according to the study, which used a microsimulation model developed by researchers at Harvard T.H. Chan School of Public Health. The model combined national natality, socioeconomic, demographic and insurance data to produce individual coverage trajectories from birth through age 18 for a nationally representative cohort of children.

The researchers from Harvard University and NORC at the University of Chicago used the microsimulation model in the absence of comprehensive claims data and follow-up periods in national surveys. These challenges have stifled efforts to track long-term childhood insurance coverage trends, they said.

However, only about 13% of U.S. children stayed continuously enrolled in Medicaid or CHIP during the model's period between 2015 and 2019. Additionally, only 30% received continuous coverage throughout childhood, with at least some parts covered by the programs.

Most children face coverage gaps

Children face a lot of churn with their insurance coverage. The study found that U.S. children made an average of 2.5 switches across insurance types -- Medicaid, CHIP, Marketplace, employment-based and uninsured -- by their 18th birthday.

What's troubling is that two in five children experienced a period of being uninsured during childhood, researchers pointed out.

They reported that only one in four children maintained continuous coverage in private non-Marketplace plans throughout childhood. Meanwhile, 42% of children were uninsured at some point during childhood -- much higher than the point-in-time estimate of 9.4% from American Community Survey data and the three-year estimate of 14.2% from the U.S. Census Bureau's Survey of Income and Program Participation.

More children in non-Medicaid expansion states faced some period of no coverage, the study also found. About 59% of children born in Medicaid or CHIP nonexpansion states were uninsured at some point, versus 36% in expansion states. Median time without coverage was also longer in nonexpansion states at 18 months compared to 12 months in expansion states.

Overall, children born with Medicaid or CHIP coverage consistently had the highest share of ever being uninsured. Additionally, if they were ever uninsured during childhood, they had the longest cumulative time without coverage in states with the most restrictive eligibility policies, researchers reported.

Medicaid reforms to affect childhood coverage

The microsimulation showed the broad reach of Medicaid and CHIP, both of which have recently experienced significant policy changes under President Donald J. Trump's far-reaching spending law, also known as the One Big Beautiful Bill. The law includes the loss of eligibility for some noncitizen children (e.g., refugees and asylees) and coverage losses for parents in expansion states because of new work requirements and more frequent eligibility checks, researchers said.

Cuts to state funding approaches in Medicaid, including provider tax reforms, will also "put pressure to state budgets and may lead to further enrollment reductions," they added.

Trump has also already directed CMS to stop approving Section 1115 waivers for multiyear continuous public insurance eligibility among children, per a July 2025 notice.

The researchers also worried about the spillover effects of changes to parental coverage, particularly in nonexpansion states that may make other, more restrictive policy changes. This occurred during Medicaid unwinding, researchers explained, when nonexpansion states faced greater declines in child enrollment after the COVID-19 public health emergency.

"Upcoming policy changes that reduce Medicaid funding and enrollment may worsen the risk of coverage gaps for children," the study concluded.

Jacqueline LaPointe is a graduate of Brandeis University and King's College London. She has been writing about healthcare finance and revenue cycle management since 2016. 

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