Levonelle is a pill used as postcoital contraception. The pill’s active ingredient – levonorgestrel – is a synthetic derivative of progesterone. The mechanism behind emergency contraceptive pills has not been fully discovered yet, but it is believed that their effectiveness is primarily based on preventing ovulation and growth of the mucous membranes of the uterus. During a normal menstrual cycle, mature egg cells are released into the ovaries, which results in increased production of progesterone and prevention of a further release of the ova. Levonorgestrel makes the body receive a signal that ovulation has occurred, and therefore the egg is not released into the ovaries. Synthetic hormones also increase the viscosity of the mucus in the cervix, which causes the sperm to encounter a serious obstacle on their way to the ovum.
The pill should be taken no later than three days after the unprotected intercourse.
According to the manufacturer, 84 percent of women manage to prevent pregnancy by taking the tablet within 72 hours, so it is extremely important to take it as soon as possible.