WASHINGTON, D.C., May 3, 2011 ( – The rate of U.S. women between the ages of 15 and 44 who have ever used the abortifacient morning-after pill has doubled since the U.S. Food and Drug Administration authorized the Plan-B drug for over-the-counter sales, according to a new study.

The study, published in the journal Fertility and Sterility, found that 10 percent of the sexually active respondents in the survey of 7,300 women between the ages of 15-44 reported ever using EC.

By comparison, just four percent of women surveyed in 2002 reported using EC.

The FDA approved Plan-B for over-the-counter use in 2006, and then lowered the age for over the counter use to 17 in 2009. The drug had been FDA-approved for prescription since 1999.

Although advocates for EC say access to the drug would help reduce “unintended pregnancies,” Megan L. Kavanaugh, a senior researcher for the Guttmacher Institute, Planned Parenthood’s former research arm, admitted to Reuters “so far there’s no evidence that this is happening.”

This finding mirrors the results of promoting emergency contraception in other countries. In the United Kingdom the government’s pilot program of distributing EC to teenagers under 16 in some areas has not only not cut the rate of pregnancy, but may actually have spurred a rise in sexually transmitted diseases (STDs). 

UK government researchers found that pregnancy rates for girls under 16 remained the same in areas where EC was handed out for free as in areas where it was not. But STD rates jumped 12 percent in those areas where the morning-after pill was made freely available compared to those where it was not.

Government statistics report that the UK has the highest teen pregnancy rate in Western Europe, and the rate of contracting STDs in teenagers under 16 has risen 58 percent within the past five years.

Emergency contraception like Plan-B works by releasing massive amounts of progesterone into a woman’s body, thereby suppressing ovulation, inhibiting sperm migration and reducing sperm capacity for fertilization. However, this can produce an abortifacient effect, whereby the influx of progesterone changes the lining of the womb, preventing an already conceived embryo from implanting. Failure to implant means the embryo starves to death.

Plan-B is not the sole EC now on the market, and newer forms of EC have more abortifacient effects. The FDA in July 2010 approved another drug, “ella”, which is designed to be taken within five days of sexual intercourse. But chemically, the drug has abortifacient properties in common with Mifepristone, a key ingredient in the abortion drug regimen RU-486.

Ella (or “ulipristal acetate”) turns off the progesterone receptors in the woman’s body, which are crucial not only for the beginning of pregnancy, but also its continuance.

Ella, however, is currently prescription-only.