It goes by various different names – emergency contraception, post coital contraception, Plan B (a common brand name) and most commonly referred to as the morning after pill; and it is the morning after pill effectiveness that is a matter of doubt for most women.

The effectiveness of the morning after pill actually goes beyond the morning after, with most brands offering protection against an unwanted pregnancy for up to 72 hours (three days) after unprotected sex and some of the newer formulations offering protection for up to 120 hours or 5 days.

Morning After Pill EffectivenessThis form of contraception can become something of a lifeline for women in several different scenarios – after spontaneous or unplanned sex, forced or non-consensual sex; or unprotected sex for any other reason such as breaking of a condom during sex; being lured into sex under the influence of alcohol or drugs etc.

We look at the different facets of the effectiveness of morning after pill –

How does the morning after pill work?

According to experts and manufacturers, the morning after pill works by preventing the ovaries from releasing an egg so that there is nothing to fertilize even if the sperm does reach.

It is also thought to work by altering the environment of the womb making it hostile to a possible pregnancy.

The morning after pill has to be differentiated from the abortion pill which is something taken by a woman to end an existing pregnancy. While the morning after pill prevents a pregnancy from occurring, the abortion pill ends a pregnancy that has occurred.

What is rate of the morning after pill effectiveness?

While the morning after pill is not a 100% effective, the failure rate is very low; well below 10% according to most estimates. As the labeling on Plan B states, “Seven out of every eight women who would have gotten pregnant will not become pregnant”.

This is not to say that morning after pill will help a woman who has gotten pregnant immediately after unprotected sex, so if conception has occurred, it is unlikely that the pill with end the pregnancy or have any negative impact on that pregnancy.

The important thing to maximize the morning after pill effectiveness is to take it as soon after unprotected sex as possible. The sooner it is taken after unprotected sex, the more effective it is likely to be in preventing an unwanted pregnancy.

How safe is the morning after pill?

There are some known side effects from this form of emerge contraception, and some women do experience some nausea, back or abdominal pain, muscle aches, headaches and so on, but this is not common and is seen to occur in less than 10% women who use it. A third of women who use it may find that their period is a bit early or a bit later than normal.

While the morning after pill effectiveness and safety are fairly well established, it is still not to be used as a regular form of contraception because the possible long term effects are not fully understood. Also it is important to follow instructions about taking the pill, such as abstaining from unprotected sex for a certain amount of time after taking it.