How does the birth control pill work?

Question

I have a friend is who very confused about how the birth control pill works, so I just want to confirm.

He thinks it works by killing off all fertilized eggs. In other words, he believes pregnancy will always happen, but it will kill the pregnancy. I told him that it is meant to work in the way that it prevents ovulation, therefore preventing an egg from even being released, but he still claims he is right.

Who is right, and can anyone provide links?

Answer 1

Sounds like the religious fundies got ahold of him.  

Chemical birth control works by stopping the ovaries from producing eggs much as if the body is already pregnant.  The extra estrogen and progesterone is what cause the common symptoms of weight gain, moodiness, and the possibility of bloodclots.  They also clear up the skin and can make period cramps milder.

Since the ovaries are not producing eggs, there's no possibility of an egg being fertilized.  In theory of course.

Lots of women get pregnant while on chemical birth control.   Most of these women go full term unless they abort the fetus.  Birth control doesn't kill fertilized eggs.  Actually, the body naturally is better at that.  Many fertilized eggs are miscarried by the body (that is not on birth control) before they even implant.

So send him to a site that explains how all this works and since he's already caught by the crazy fundies, he'll not believe you and keep spouting that nonsense, but at least deep down he'll know the scientific truth.

Answer 2

He's very wrong.  Think of it as the pill making your eggs duds so pregnancy cannot happen.  

Answer 3

You're both right.  The Pill is supposed to essentially trick your body into thinking it's already pregnant, which should prevent ovulation.  However, if you do ovulate when taking The Pill, the hormones create an unhospitable environment for a fertilized egg, preventing implantation from happening.

So while the primary mechanism is to prevent ovulation, the "back up" method can indeed cause a very early termination--you would just have your period as scheduled and never know that the egg had been fertilized.  However, that isn't something that hormonal birth control manufacturers generally advertise.

http://www.womens-health.co.uk/birth_con...

http://www-tech.mit.edu/V121/N4/col04vee...

Answer 4

The pill works in 3 ways.

1. Primarily it works by keeping you from ovulating.  Basically it tricks your body into thinking you are pregant, so you don't make eggs.  No egg= no baby.

2.  Second, it thickens the cervical mucus and makes it hostile -- so the sperm can't get through.  No sperm to meet the egg=no baby.

3. Third (and this is what your friend is talking about) IF there is an egg and IF a sperm gets through, it changes the uterine lining so a fertilized egg can't implant.  

For some women, even the smallest chance of this third thing happening (and it is a very small chance) is sufficient that they do not feel comfortable using birth control pills. (Or any other hormonal methods, all of which CAN cause a fertilized egg to not implant.)  But if you comfortable with it (even in women who don't take pills, most fertilized eggs fail to implant -- so a woman using no BC at all would probably experience this even more often!) then the pill is a good method -- and in any case, until the egg implants you are not pregnant, so the loss of the egg would be neither an abortion nor a miscarriage. (You can't miscarry if you aren't pregnant.)

Answer 5

It's all about the hormones. Maybe you should send him off to this site. Don't forget to tell him the stork was shot down yesterday.

Answer 6

No, birth control doesn't kill off a fertilized egg, it prevents an egg from being released (prevents ovulation)

He may be confused with the morning after pill, which prevents fertilization and/or in some circumstances prevents a fertilized egg from being implanted.