A new contraceptive pill is making its round in the prevention of pregnancy of women who opt to have unprotected sex, which could have an effect for as long as five days.

According to new study, ellaOne, a new type of drug ulipristal acetate, has been found out to significantly decrease the risk of pregnancy by nearly half.

Levonorgestrel, known under brand names like Plan B and Levonelle, is currently the most used emergency contraceptive pill in the market. It is widely available in markets in worldwide, with many countries not requiring any prescription.

The new pill, on the other hand, is only sold in European countries and can only be purchased if prescribed by a doctor.

In the study, experts observed about 1,700 who were between 16 and 36 years old. They were given emergency contraceptives after three to five days of having sex. One group which was about half the participants was given Plan B, while the rest was given ellaOne.

The researchers recorded 22 pregnancies in the Plan B group and 15 pregnancies in ellaOne group. Headache was a common side effect to both groups.

It was concluded that the women who took ellaOne only had 1.8 percent chance of getting pregnant, while those who took Plan B had a 2.6 percent chance.

Plan B works by interfering during the early stages of ovulation. EllaOne, meanwhile works before the ovulation thus delaying the release of the egg. Doctors see this as the reason why ellaOne can work for up to five days.

The study was organized by HRA Pharmacy, the manufacturer of ellaOne. Drug regulators in Europe just approved the pill in 2009. HRA Pharmacy did not other details as to where else they have submitted the pills for approval.

Authorities warn, however, that the new pill does not offer security. They suggest that women should take contraceptives as soon as possible after engaging in an unprotected sex.