Texas has long been at the forefront of the battle to defund Planned Parenthood.

In 2013, the state successfully cut the network of clinics out of its public family planning program for low-income women.

Now researchers at the University of Texas have figured out what happened next: Fewer women filled birth control prescriptions — and more low-income women had babies.

The new study, published Wednesday in the New England Journal of Medicine, is the first to look at what happens to women when a state specifically excludes Planned Parenthood from public programs. While some have argued that women would just seek care elsewhere, this new research shows the opposite: When Planned Parenthood becomes less accessible, women just get less care.

Without Planned Parenthood, prescriptions for the most effective birth controls dropped by a third

The Texas Policy Evaluation Project at the University of Texas used pharmacy claim data to understand what types of birth control women used before and after Texas cut Planned Parenthood from its public family planning program. This is a program that serves women who earn less than $1,800 a month if they are single (or less than $2,426 per month if they have a child).

The data isn't able to show a causal relationship; it can't say changes happened specifically because of the policy change. But it does demonstrate some very big changes that happened to Texas women in the counties that used to have Planned Parenthood as part of their networks.

For example: Prescriptions for long-acting, reversible contraceptives including intrauterine devices (IUD) and birth control implants plummeted by 35.5 percent in counties where Planned Parenthood clinics shuttered after the new law. When Planned Parenthood was part of the Texas program, 1,042 women used this type of birth control over the course of three months. Afterward, it was 672.

Over the same time period, prescriptions for short-term hormonal birth control, like pills and patches, held relatively constant. Amanda Stevenson, who led the Texas study, says that reflects the relative ease of prescribing the birth control pill over an IUD or implant — both of which require the physician to actually place the contraceptive.

"The provider doesn't need to have any specialized skills to give a prescription for an oral contraceptive," says Stevenson, a researcher with the Texas Public Policy Evaluation Project. "That's a great feature of those methods, but the problem is those methods aren't the most effective."

Planned Parenthood had specialized in providing long-acting reversible contraceptives (LARCs). Without those clinics, women used that type of birth control less.

And this worries public health researchers: LARCs are especially important because they are way more effective than pills or patches. The Pill has a 6 percent failure rate. So out of 1,000 women taking birth control pills, 60 will become pregnant in a typical year. Among women who use an IUD or implant, that number will be between two and eight (depending on which specific type of contraceptive they use).

The medical group that represents gynecologists now recommends LARCs as the first-choice contraceptive for most women of reproductive age — but in Texas, they're becoming harder to get.

Most women using injectable contraceptives just stopped

The Texas women's health program had about 8,000 women using the injectable contraceptive Depo-Provera, which requires a shot every three months for the medication to remain effective. Even before Planned Parenthood was cut from the Texas network, only 56.9 percent of patients in counties with Planned Parenthoods would return for an on-time follow-up shot every three months.

Numbers fell much lower, though, after the 2013 cuts. Counties previously served by Planned Parenthood clinics saw a 21.2 percentage point decline in women returning for on-time shots — while numbers in counties that had never had Planned Parenthood clinics essentially held steady.

More women on Medicaid had babies 18 months after the Planned Parenthood cuts

Less access to birth control correlated with an uptick in births among certain Texas patients.

This design of this part of the study is a bit complex, and you can read more about it in the paper itself. It essentially involves comparing women who were using the Depo shot at the end of 2012 — right before the Planned Parenthood cuts — to women who were using the Depo shot at the end of 2011 and experienced no such disruption.

Researchers find that the women who lived in places affected by the Planned Parenthood cuts had 27 percent more births than the women using Depo in the year prior.

This was not just a sudden increase in Texas women having babies. Births among women who'd never had a Planned Parenthood clinic in their county to begin with actually decreased slightly over the same time period.

"We saw a 40 percent decrease in women not returning for their Depo shots, and a 27 percent increase in births," says Stevenson. "Those two numbers tell a pretty consistent story about contraceptive use declining and births increasing."

The story here is consistent: Defunding Planned Parenthood means less birth control, more births

Congressional Republicans have, so far, failed to defund Planned Parenthood on a national level — despite multiple attempts to do so.

This new Texas study is important because it demonstrates that there is a risk that comes with cutting Planned Parenthood out of public programs: Women won't get the care that they used to, and births can increase as a result.

"This directly contradicts the claim that other providers will simply take up the slack and that they'll meet the demand currently being met by Planned Parenthood providers," Stevenson says. "We can say, after this study, that isn't the case in Texas."