How Does the Morning After Pill Work?

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The morning after pill should be a last resort as a form of contraceptive and responsible couples should use condoms, other oral contraceptives, IUDs, sponges and sexual techniques as their main way of preventing a pregnancy; particularly as condoms will help protect against other problems too such as sexually transmitted diseases and infections (in fact so much is this the case that one brand of the pill is known as ‘Plan B’). A condom will also reduce the chance of an unwanted pregnancy by 90-95%. The various sexual techniques can also allow a couple to have unprotected sex (as long as they are both certain they are free from STDs) without risking becoming pregnant. These generally involve pulling out for the vital moment, or pleasuring each other in different ways. It is also possible to time sex in such a way that the chances of the woman becoming pregnant are almost non existent by engaging in intercourse immediately after the woman has finished her menstrual cycle (before the egg has had a chance to enter the fallopian tube). None of these methods are one hundred percent guaranteed however and so other forms of contraception are recommended for full intercourse.

However hindsight is a wonderful thing, and should a couple have sex without using another form of contraceptive or should the contraceptive fail (for example if the condom breaks inside the woman) then the ‘morning after pill’, such as ‘levonorgestrel’, is an alternative solution that can terminate unwanted pregnancies after the intercourse has taken place. But how does the morning after pill work?

Well when asking ‘how does the morning after pill work’ it is important to first understand a little bit about the female menstrual cycle. A woman’s reproductive system is very complex (just as any woman) and their menstrual cycle involves multiple hormones. Shortly after the woman ends her period her pituitary gland will begin its monthly cycle by secreting FSH – also known as ‘follicle stimulating hormone’. It is this hormone that instructs the ovaries that the follicles need to be prepared for ovulation. One follicle then develops and begins to emit oestrogen, the ‘female hormone’ (which is also what causes women’s breasts to swell up as they near the end of their cycle). This will thicken the uterine lining ready to accept the fertilised egg. At the same time the ovaries will also begin to secrete progesterone.

After a certain point the hypothalamus and pituitary gland will sense the blood levels of oestrogen and progesterone are high enough and will then release an egg into the fallopian tube. This is what is known as ‘ovulating’ and at this point sperm will have a 24 hour window in which to reach it in order to reproduce.

If after two weeks the woman doesn’t become pregnant she will then begin menstruating and the cycle will begin anew. If however she has become pregnant, then the fertilised egg will travel down the fallopian tube to the uterus (womb) where ‘implantation’ will occur. This means the egg will be implanted into the womb where it will be nourished by the mother until it grows into a human being. But how does the morning after pill work to prevent a pregnancy from occurring? Well, although each egg only has a 24-hour period in which it can be fertilised, sperm can live for three days within a woman’s body. This means that if she has sex anywhere up to three days before ovulation she may still become pregnant. Thus contraceptive pills work in one of three ways – they can delay the release of the egg thereby preventing the possibility of the egg becoming fertilised after sex, they can prevent the fertilised egg from implanting in the womb, or they could prevent or delay the release of the egg again preventing fertilisation after sex. The morning after pill is not 100% effective then but will drastically reduce the chances of a pregnancy occurring.

Answering the question ‘how does the morning after pill work’? However raises several issues. One such issue is the claim made by some critics that by preventing implantation the pill is in fact abortive rather than contraceptive as the egg is already fertilised. However this is debatable and when it is considered that a fertilised egg before implantation no more satisfies the 7 criteria necessary for life than does the sperm on its own. This is an ethical decision that is the sole decision of the person taking it. It also raises the question of possible side effects and health risks, and the list of possible side effects includes cerebral hemorrhage, cerebral thrombosis, melasma, migraines, headaches, arterial thromboembolism, retinal thrombosis, haemolytic uremic syndrome and dizziness among others. However these side effects are rare and provide little threat to most responsible users.

The mechanisms of action for the morning after pill are complex and varied. This ensures that the pill remains a mostly reliable form of contraceptive but also raises various other issues. Studies into the long term effects of the morning after pill are limited and though it seems mostly safe, it should still be used sparingly.

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About the author

Adam Sinicki
Adam Sinicki

Adam Sinicki is a full time writer who spends most of his time in the coffee shops of London. Adam has a BSc in psychology and is an amateur bodybuilder with a couple of competition wins to his name. His other interests are self improvement, general health, transhumanism and brain training. As well as writing for websites and magazines, he also runs his own sites and has published several books and apps on these topics.

Follow Adam on Linkedin: adam-sinicki, twitter: thebioneer, facebook: adam.sinicki and youtube: treehousefrog

3 comments

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  • I agree with the previous comment. This article says "contraceptive pills work in one of three ways" but it doesn't say if the "morning after" pill works in all three ways or just preventing implantation.

  • there isn't an answer in this article for question that how does the m.a.p. work? just telling about menstrual cycle but what about pill?

Adam Sinicki By Adam Sinicki

Adam Sinicki

Adam Sinicki

Adam Sinicki is a full time writer who spends most of his time in the coffee shops of London. Adam has a BSc in psychology and is an amateur bodybuilder with a couple of competition wins to his name. His other interests are self improvement, general health, transhumanism and brain training. As well as writing for websites and magazines, he also runs his own sites and has published several books and apps on these topics.

Follow Adam on Linkedin: adam-sinicki, twitter: thebioneer, facebook: adam.sinicki and youtube: treehousefrog