A study from Obstetrics & Gynecology medical journal found that people with private health insurance are more likely to have medical bills in debt collection after having a baby than during pregnancy.

Researchers used data from Blue Cross Blue Shield of Michigan insurance plan, which covers 3.5 million people in the state, and matched it with credit reporting from Experian. They then looked at the group of pregnant women (defined as those who gave birth between February and July 2021) and compared it to postpartum women (those who gave birth between January and June of 2020.) They found that medical debt was common, with 15% of pregnant women having some medical debt. But medical debt was at 18%, three percentage points higher, with the postpartum group — a statistically significant difference.

In other words, having a baby pushed more people into medical debt, even when they have insurance. Lead research author Michelle Moniz, along with her co-authors, wrote the study “suggests that these health care expenses are objectively more than many commercially insured families can afford, leading to medical debt.”

The study also found that, not surprisingly, postpartum individuals in the lowest-income neighborhoods were the most likely to have medical debt in collections.

This research comes as some states are considering taking funds from the Biden administration to expand Medicaid postpartum care from just 60 days after delivery to a full year post-delivery. Medicaid recipients do not have to pay out-of-pocket for maternity or newborn care. You can see if your state has expanded Medicaid coverage for new moms at the Kaiser Family Foundation.