An online survey of more than 1,000 women and women who have used at least two abortion pills found that women who use an injectable form of RU-486 are more likely to have fewer unintended pregnancies than those who use oral pills.
The RU-494 form, which can also be taken as an injection, was most popular among women using oral pills and the RU-498 form, a liquid formulation, was popular with women using injectable pills.
The RU-488 pill, which was approved by the US Food and Drug Administration in 2009, was approved in July this year, and RU-484 in October.
The new study, published in the American Journal of Obstetrics and Gynecology, also found that more than half of women who used RU-496 experienced a decrease in their risk of having a second unintended pregnancy, while the remaining women experienced a slightly greater increase.
However, the RU+4 and RU+5 forms of RU486 had a significantly higher incidence of unintended pregnancies compared to the RU486 pill, the researchers said.
The results suggest that the use of RU+48, RU+49 and RU+.5 can decrease the number of unintended pregnancy occurrences by up to 1,700 per 100,000 users, the authors said.
According to the authors, the new findings also show that women should not stop using RU+486 until they have used an injector of RU-, RU+ or RU-4, but that the effectiveness of RU48 should be assessed on a case-by-case basis.RU-486, which is the only approved drug for abortion in the US, has been the standard method of abortion since its approval in 2009.
However in recent years, more and more countries have introduced new forms of abortion pills, including RU-3, RU-5 and RU-.6.
RU-48, the most widely used RU486 in the world, has also been increasingly replaced by RU-8, which has been more commonly used in Europe, and the newer RU-9.
“In the United States, RU486 was the first drug to be approved in the 21st century and it is one of the safest forms of emergency contraception available to women,” Dr Jafari said.”RU486 was approved to prevent the abortion of a fetus, but the effectiveness is often limited by the fact that the abortion pill can only prevent fertilisation and not implantation.”RU-.4, which also acts as a contraceptive, is currently the most commonly used RU-, but it was replaced in 2014 by RU-.8.
RU-.5 is currently used in only about 1% of the world’s countries, and is widely considered the safest and most effective form of abortion pill available.
The findings suggest that RU486 should be more widely available to pregnant women and is therefore likely to be more effective in preventing pregnancy, Dr Jaffari said, adding that the RU-.4 form was less likely to cause abortions in some women, and it was more likely for women who had undergone an abortion procedure, or had an ectopic pregnancy.
“Women who have undergone an induced abortion and/or a miscarriage have higher risk of an ectopy, so it’s a very strong indication that RU-485 is the safest form of emergency contraceptive available,” Dr Lavinia S. Dyer, of the University of Florida, told Al Jazeera.
Rochelle O’Leary, a professor of obstetrics at Johns Hopkins University in Baltimore, said the study was important because the RU48 and RU.5 pills are both very effective at preventing pregnancy and are commonly used to prevent pregnancy for the same reason, but RU-490 is more widely used because of the increased availability of it in the UK.
“They are a good first choice because they are safe, they’re very effective, and they’re used to treat a variety of different things,” she said.