The Affordable Care Act (ACA) requires employer-based insurance plans to cover maternity services, but plans are allowed to impose cost sharing such as copayments and deductibles for these services. This study aimed to evaluate trends in cost sharing for maternity care among working women in employer-based plans, before and after the ACA. Our data indicate that between 2008 and 2015, average out-of-pocket spending for maternity care rose among women with employer-based insurance. This increase was largely driven by increased spending among women with deductibles. When we controlled for potential confounders, we found that out-of-pocket spending was higher for lower-income working women in 2008–13, but disparities disappeared in 2014–15 because of a continued rise in spending among higher-income working women. Policies that aim to lower out-of-pocket spending for maternity care could reduce a significant financial burden on families.