States have passed 288 abortion restrictions in the past five years — an entire quarter of those enacted since the Supreme Court recognized a legal right to abortion.

When the Supreme Court ruled, in the 1973 Roe v. Wade decision, that women had a legal right to abortion, states responded with a wave of restrictions. That year alone, states passed 81 laws that limited abortion access, things like 24-hour waiting periods prior to the procedure or requiring the consent of a woman's spouse.

But the restrictions of 1973 are dwarfed by recent activity. In 2011, states passed 92 abortion restrictions — the most since the nonprofit Guttmacher Institute began keeping count. When you look at things in the aggregate, you see that the past five years account for 27 percent of all abortion passed since Roe took effect.

A Republican takeover of state legislatures helped pro-life groups win

There are two factors that likely contribute to the rise in abortion restrictions. First was the national health reform debate. One of the last sticking points to get resolved there was whether the plans offered on the exchanges would pay for abortions.

In response, President Obama issued an executive order that prohibits tax subsidies from paying for abortions, except in cases of rape and incest. Instead, insurers would need to use the part of the premium paid by individuals to cover pregnancy terminations.

Enough anti-abortion legislators were won over by this executive order to pass Obamacare. Many pro-life groups, however, still contend there isn't a strict enough firewall between the tax subsidies that insurers receive and the abortion claims they pay out.

They took their lobbying efforts to the state legislatures — and found a receptive audience. A few months after Obamacare passed, Republicans took increasing control of state houses. In 2010, Republicans ran 14 state governments. By 2011, that increased to 26.

So by the end of 2010, abortion had become a prominent political issue — and Republicans had more political clout to take action.

20-week bans and targeted regulations of clinics have skyrocketed

Abortion restrictions often come in waves; one state will pass a new type of law, and then others follow. Nebraska, for example, passed the first 20-week abortion bans in 2010. Eight more states have since gone on to enact similar legislation.

Another case: Between 2011 and 2014, the number of states requiring abortion providers to have admitting privileges at a local hospital jumped from two to 11.

The waves of new abortion restrictions tend to cluster around specific approaches to regulation. About half of those enacted since 2011 fall into four categories: bans on abortion at 20 weeks, limitations on insurance coverage of abortion, limitations on medical abortions, and targeted regulations of abortion providers (like the admitting privilege laws).

These are the types of laws that will soon be tested in a pending Supreme Court case, Whole Women's Health v. Texas. That lawsuit argues against a new Texas law that requires abortion clinics to become certified as ambulatory surgical centers, making costly upgrades to their facilities. About half of Texas clinics have closed after this law was enacted in 2013.

These laws have real effects on real people

Researchers at the University of Texas recently surveyed 23 women in the state, who attempted to get abortions in the wake of the new certification law. My colleague Emily Crockett wrote about what they found:

Five of these women had abortion appointments that were abruptly canceled after the clinic closed, 15 tried to make an appointment but were turned away because the clinic had recently closed, and three were Texas residents who ultimately crossed the border into Albuquerque to have their procedure done. Of the 23 women interviewed, two couldn't overcome the financial and logistical obstacles it would have taken to get an abortion somewhere else, so they continued their unwanted pregnancy. Eight women were delayed more than one week. Two sought abortion care in the first trimester, but were delayed so long that they couldn't get an abortion until the second trimester — which is a more expensive and riskier procedure. (Second-trimester abortions still only have a 1.3 percent risk of major complications, but that's more than 20 times higher than the risk for a first-trimester abortion.)

You can read more from about the Texas law here — and an overview of how America regulates abortion here.