Expectant mothers who have a change of heart after beginning a chemical abortion now have the ability to reverse the process, according to a new study.

A team of doctors and researchers found that heavy doses of progesterone, a hormone found in the ovaries and placenta, can safely reverse the effects of commonly used oral abortifacients. The group followed the cases of hundreds of women who changed their minds about having abortions. They found that early intervention and heavy doses of the hormone succeeded at keeping the baby alive in 64 to 68 percent of cases.

"Intramuscular progesterone and high dose oral progesterone were the most effective," the study published in the journal Issues in Law & Medicine said. "The reversal of the effects of mifepristone using progesterone is safe and effective."

Study author George Delgado said he hopes the study can alleviate regret among women who start an abortion but later change their minds. Even more promising is the fact that the initial dose of mifepristone, which is designed starve or suffocate the baby by cutting off progesterone receptors, did not increase the risk of birth defects, meaning babies are able to recover from the trauma of the chemicals designed to kill them.

"Women who change their minds after starting a medical abortion now have a second chance at choice," Delgado said in a statement. "Using progesterone to reverse the effects of mifepristone is effective and does not increase the risks of birth defects."

Abortionists have used mifepristone to end the lives of unborn babies since 2000. Administering the drug, the active ingredient in the RU-486 pill, is the first step toward a medical abortion—which accounted for 31 percent of all non-hospital abortions in 2014. Mifepristone blocks progesterone receptors in the uterus, cutting off the baby from receiving oxygen and nutrients. Once the drug has been administered, pregnant women then take misoprostol to help expel the baby. Taken together those drugs have a 93 to 98 percent effective rate for termination, according to Planned Parenthood.

The new research said progesterone doses taken before misoprostol is administered can safely reverse the effects of the initial RU-486 dose, allowing the baby to continue receiving sustenance. The doctors followed up on a Japanese study that found 100 percent of rats could survive mifepristone doses using progesterone compared with only 33 percent who survived without the intervention. Studies in humans have shown that only 8-25 percent of babies could survive mifepristone taken alone without any intervention.

The study found that 261 babies were able to survive with the help of progesterone regimens administered either orally—68 percent survival using a twice daily 400 mg pill—or by injection—64 percent rate. Those rates were more than double what was expected without treatment. Progesterone therapy helped deliver 257 babies, while another 4 were lost to natural miscarriage after more than 20 weeks gestation.

The team received positive feedback from participating pregnant women. More than 300 doctors treated the women who changed their minds and solicited responses from their subjects. One woman told the researchers that progesterone therapy "changed my entire world by helping me that night. This is the best feeling in the world and nothing else matters. Thank you." Another added, "I just wanted to say, thank you from the bottom of my heart," according to a release from the Culture of Life Family Services in San Diego, where Dr. Delgado serves as medical director.

Seven of babies suffered birth defects, equal to the rate among women who never ingest abortifacient drugs. Those defects ranged in severity from hearing loss to a heart murmur. Not all participants in the study opted to continue it. More than 7 percent of the women who called in to inquire about progesterone therapy followed through with abortion—39 by taking misoprostol, 7 using surgical abortion, and 11 by other unspecified means.

The authors noted that the study was voluntary, rather than randomized or placebo-controlled. They noted that using a placebo would be unethical because it would deceive women who "want to save the pregnancy." The study's authors say more research is needed to best determine proper dosage and delivery of progesterone.