It can seem like just a mirage created by the summer heat: only a few weeks ago the Supreme Court actually handed down a decision that progressives could celebrate. It held that the Affordable Care Act is constitutional, including the individual mandate, meaning that implementation can roll on full steam ahead. I was one of the first to celebrate, in particular for all the ways that the law will help women who need healthcare (which is all of us). As Katha Pollitt recently wrote here, women will benefit dramatically from the ACA. The law bars practices like charging women more just for being women, dropping women’s coverage if they become pregnant or sick, and denying coverage due to “pre-existing conditions” like having had breast cancer or being a victim of domestic violence. It adds new benefits like birth control coverage at no cost to the patient, expanded coverage of preventative services like prenatal care, mammograms, pap smears and bone-density screenings through Medicare, and requiring insurance companies to cover maternity care.

But one aspect of the Supreme Court’s decision could have some very bad results for women: the ruling that states can opt out of the Medicaid expansion. While this could end up harming men and women, women in particular stand to suffer if states refuse to participate in the program.

The Medicaid expansion is a crucial component of the law’s overall goal of extending coverage to over 30 million uninsured Americans by 2019, covering almost half of the total number of people the bill promised to insure. Originally, the law included a provision that the federal government could take away all of a state’s Medicaid funding if it refused to go along with the expansion, which all but ensured participation. But the Court ruled that such a maneuver was unconstitutional. Just a few days after the decision was announced, seven Republican governors said they would flat-out reject the money to expand Medicaid rolls, with at least eight more looking to follow suit. More have said no since then.

This could create a no-man’s land for those who earn less than 100 percent of the federal poverty line, making them ineligible for tax subsidies to help them buy insurance, but don’t qualify for their state’s (unexpanded) Medicaid program. These Americans are surely struggling to get by, but not quite enough to get health coverage promised to those above and below them.

And women are likely to fall into this chasm. Remember that unexpanded Medicaid does not cover most childless adults. Currently, a woman must meet both categorical and income criteria to qualify for Medicaid: she must be pregnant, a mother of a child under age 18, a senior citizen or have a disability, and each category has income criteria, which differ state by state. Given that women are more likely to be pregnant (duh) but also to fall into the other categories, they are already the majority of enrollees in the program. However, given that many women don’t meet categorical criteria, many don’t qualify, no matter how poor they are. Over 17 million women lived in poverty last year, compared to 12.6 million men.

By 2016, 13.5 million women were expected to get coverage under the Medicaid expansion. That figure is now in danger. As the Kaiser Family Foundation reported before the Supreme Court decision, “Medicaid will be the foundation of health coverage expansions to very low-income women.” But not if some Republican governors get their way.

Many of the states already rejecting the expansion are home to the greatest number of women who would benefit. Texas and Florida top the list for the most uninsured women in their states: about 2.4 million and 1.5 million, respectively, and both states plan to refuse the expansion. (Some of these women were supposed to get coverage through the Medicaid expansion, but some will still qualify for the subsidies and be able to buy insurance in the state exchanges.)

Using Kaiser’s predictions, I calculate that there are over 4.2 million women who would be eligible for the Medicaid expansion by 2014 in the states either refusing or indicating they will refuse to participate. That’s a huge chunk of the 10 million women that were expected to be covered by that time through Medicaid.

Those are the immediate impacts on low-income, uninsured women. The ruling may have other far-reaching impacts on women’s lives, however. As Jessica Mason Pieklo writes at RH Reality Check, the idea that the federal government can’t withdraw all Medicaid funds from states that don’t follow federal requirements might have other consequences. The first may be states that are trying to prevent Medicaid from contracting with providers that also offer abortions (i.e., in many cases, Planned Parenthood). Such a case is going on in Indiana right now. As Pieklo writes,

Thanks to the majority in NFIB v. Sebelius, conservative states looking to enact state-wide funding bans may have the framing necessary to pin the federal government. That’s because the language of Roberts’ opinion as to the Medicaid expansion is vague enough to argue that the federal government can’t coerce a state into funding Planned Parenthood by threatening to withhold all of that state’s federal Medicaid money, especially, since conservative states argue, they believe cutting Medicaid funds is the only way to guarantee state dollars do not fund abortion services.

Planned Parenthood and its affiliate centers provide services to 3 million people annually, including 4 million tests for sexually transmitted infections, 770,000 Pap tests and 750,000 breast exams. Banning Medicaid from contracting with Planned Parenthood will hurt the low-income women who need these services—but states may now have a legal leg to stand on if they try to do just that.

Perhaps the worst thing of all? The excuse that Republican governors are using to get out of the Medicaid expansion may not even hold up. They claim to be worried that even though the federal government will pick up the whole tab for the first few years, the portion they’ll have to pay after that (10 percent) is too burdensome on their budgets. Yet there is evidence that expanding Medicaid could actually help their finances. Rejecting the Medicaid expansion may not even make fiscal sense, but no matter what it doesn’t make moral sense. It could leave millions of women exposed, unable to afford health insurance but not able to participate in Medicaid.