A new report by the Guttmacher Institute, a reproductive rights think tank, shows that the abortion rate in the United States fell 13 percent between 2008 and 2011, hitting its lowest point in 30 years.

The upshot is that American women are probably having fewer abortions because they’re facing fewer unplanned pregnancies. So far, it looks like restrictive abortion laws aren’t a key factor here. If increasing numbers of women had been deprived of abortions because such laws restricted access, the birth rate should have gone up too — but, in fact, it went down. Then again, the recent burst of anti-choice legislation at the state level didn’t get underway until 2011, so the effects of those laws have yet to be quantified.

The study’s authors suggest two factors that best explain the drop in unplanned pregnancies: better contraception and a worsened economy. More women are using highly effective, long-acting forms of contraception such as IUDs, compared to more failure-prone methods like the Pill and condoms. Use of such long-acting contraceptives nearly tripled between 2006 and 2010 among women accessing federally subsidized contraception, rising from 4 percent to 11 percent. And then there’s the economy: In 2009, nearly half of surveyed women told Guttmacher researchers that the recession made them want to delay childbearing.

However, the authors caution that if more women are resorting to self-abortions that don’t show up in the official statistics, the large drop in the abortion rate may be exaggerated.

Humans have attempted to induce miscarriages with herbs, drugs, and physical ordeals (like scalding baths and abdominal massage) since time immemorial — largely without success. Finally, in the late 1980s, an early abortion drug became available that actually works. It’s called misoprostol, and its best-known official use is to prevent ulcers in people who take a lot of aspirin-like drugs. Misoprostol also forms half of the drug cocktail that doctors use for medication abortions.

Soon after misoprostol hit the world market as an ulcer drug, its abortifacient potential was discovered and exploited. Misoprostol became a popular method of abortion in South America and the Caribbean, where abortion tends to be tightly controlled, if not criminalized. Doctors in the Dominican Republic remember 1986 as the year they stopped seeing septic surgical abortions in the ER; when the drug arrived on the island, the back alley surgical abortionists went out of business. Knowledge of misoprostol as an abortifacient has since diffused to Mexico, the border states, and even to some immigrant communities in New York City.

Reliable data on self-abortion rates in the United States are maddeningly hard to come by. As far as we know, self-abortion remains rare in absolute terms. In a national survey of nearly 10,000 women seeking abortions at clinics, 1.2 percent of respondents admitted having tried to self-induce a miscarriage with misoprostol. Surveys at abortion clinics may underestimate the incidence of self-induction. After all, women who successfully self-induced might not ever visit an abortion clinic. Women may also be reluctant to report self-induction attempts because they believe the practice is illegal or because there’s a social stigma attached.

A simple Google search turns up countless overseas pharmacies openly selling misoprostol, often under the brand name Cytotec, and offering to ship it to the United States. Some sites openly tout misoprostol as an abortion pill. Technically, it is illegal to buy misoprostol from an international pharmacy without a prescription, but US consumers are rarely prosecuted for buying the drug or other noncontrolled substances online.

Women on Waves, a Dutch pro-choice group, offers detailed, medically accurate, onlineinstructions in multiple languages on how to perform an abortion with misoprostol. The group’s website urges women to seek an abortion from a medical professional if at all possible and cautions them not to attempt to self-abort alone. It also gives information about potential complications and offers guidelines for when to seek medical attention. The site warns that the drug should only be used in the early weeks of pregnancy because the risk of complications rises significantly thereafter.

National statistics on self-induction obscure the fact that the popularity of misoprostol for self-abortion varies widely by location. Women in communities along the US-Mexico border have been quietly using the drug for years. In Mexico, misoprostol can be bought over-the-counter without a prescription. Obtaining the drug, for some, can be as easy as walking over a pedestrian bridge and paying cash at one of the many pharmacies that cater to Americans seeking cheap prescription meds. Some enterprising vendors buy Mexican misoprostol and resell it on the black market in Texas, often at flea markets.

Dr. Lester Minto of Harlingen, Texas estimated in January that he’d evaluated about 200 pregnant patients since Texas’s new abortion barred him from providing abortions this fall after over 30 years in practice. Of these women, about 100 returned to have Minto resolve incomplete miscarriages, which were almost certainly induced by misoprostol they procured on their own. This kind of miscarriage management is still legal in Texas.

A staffer at an abortion clinic in nearby McAllen said her clinic saw about one failed misoprostol self-induction a day, before the clinic was forced to stop providing abortions this fall. Minto said he saw about one admitted failed self-induction per month before the law.

Before the law went into effect, the Rio Grande Valley, a region the size of Connecticut in the southernmost tip of Texas, had two abortion clinics. Now it is without an abortion provider and women seeking a clinic abortion must make a round trip of at least 300 miles to get one. Official confirmation remains elusive, but anecdotal evidence points to an increase in misoprostol self-inductions since the law went into effect.

An abortion provider in Missouri, a state with particularly onerous legal obstacles to abortion, told ThinkProgress that some of her patients attempted to self-induce with pills from the internet because they didn’t think they could make the trip to Saint Louis for a clinic abortion.

A Pennsylvania nurse was charged in December with performing an illegal abortion for allegedly giving abortion pills from the internet to a 16-year-old girl.

Again, the new Guttmacher study only tracks abortion rates through 2011. As the authors note, the national flurry of anti-choice legislation dubbed by prochoice groups as a “war on women” didn’t really get underway until 2011, so the effects of these laws on abortion and self-abortion rates are still unknown. If the experience of the Rio Grande Valley is any indication, self-induced abortions may become increasingly common as restrictions on legal abortion tighten.