Norlevo (similar to Levonelle in the UK) one step is commonly known as 'the morning after pill'. It is used to reduce the chances of becoming pregnant after unprotected sexual intercourse. Levonelle one step tablets contain the active ingredient levonorgestrel, which is a synthetic derivative of the naturally occurring female sex hormone, progesterone.
It is not fully understood how this medicine prevents pregnancy. It is thought to work by preventing ovulation and fertilisation and also by altering the lining of the womb, depending on which stage of the menstrual cycle the woman is at.
In a woman's normal menstrual cycle, an egg matures and is released from the ovaries (ovulation). The ovary then produces progesterone, which prevents the release of further eggs. Levonorgestrel, tricks the body processes into thinking that ovulation has already occurred, as it provides high levels of synthetic progesterone. This prevents the release of eggs from the ovaries.
Levonorgestrel also increases the thickness of the natural mucus at the neck of the womb (cervix), making it more difficult for sperm to cross from the vagina into the womb. By preventing sperm entering the womb, successful fertilisation of any egg that is there is less likely.
Levonorgestrel is also thought to alter the lining of the womb, preventing it from being prepared for a fertilised egg. This means that if an egg is released from the ovaries and is fertilised, it cannot implant into the womb and therefore pregnancy is avoided.
The whole process from fertilisation to implantation in the womb can take up to three days, so the morning after pill can only stop a pregnancy for up to 72 hours after unprotected sex. The sooner it is taken after unprotected sex, the more effective it will be.
There is one tablet to be taken. Previously, the morning after pill consisted of two tablets that had to be taken twelve hours apart. Studies have since shown these tablets were equally effective if they were taken together. Levonelle one step contains one double strength tablet. It has been phased in to replace the old Levonelle product that contained two tablets. With Levonelle one step there is no second tablet to remember to take twelve hours after the first. The new double strength tablet should be taken as soon as possible, preferably within 12 hours and no later than 72 hours, after unprotected sex.
It is estimated that 85 per cent of pregnancies will be prevented if this morning-after pill is taken within 72 hours of unprotected sex. The tablet is more effective at preventing pregnancy the earlier it is taken, so it is important to take it as soon as possible after unprotected sex, rather than delay to the third day.
