How exactly does birth control work to prevent pregnancy?

the pill,or birth control,contains just oestrogen or oestrogen and progesterone.this makes oestrogen levels high so it stops the FSH levels rising,FSH makes the eggs mature in an ovary,and stops LH from realising the matured egg. If Oestrogen levels are high then it stops the rest of the cycle continuing,this means stopping an egg from maturing and being released from the ovaries.

Sorry, should have been a bit more specific. I edited my question….and yes, I know what cause pregnancy…?

Oh okay, thanks…that is exactly what I was asking. :]

Ok, I was not sure, but after the edit makes my question look stupid, this is why after a post is made, it should not be changed.

its ok :D

I know, I apologize. It’s my fault, I should have been more specific and added details when I first asked the question. :]

It releases a hormone that prevents an egg from releasing from the ovary.

The simple answer is they mimic pregnancy, and pregnancy obviously is one of the times when its physiologically normal for a women to not be able to concieve. As Lizzie mentioned, the combined pill prevents ovulation. This is because in addition to everythjing else oestragen does in the body, it also acts back on the brain to prevent the release of more gonadotrophin releasing hormone, which subsequently prevents the release of FSH and LH. In other words, oestragen regulates its own secretion. So if oestragen levels are already high, no other hormones will be produced. The progesterone part of the pill makes the cervical mucus impenetratable to sperm. Most progesterone only pills only work by this mechanism, which is why its critical to take the pill at the same time everyday - the effects only last about 24 hours. There are some types of progesterone only pill which also prevent ovulation, but most work only by thicking the mucus.

Oh and I forgot to mention - depo provera is progesterone only, but it does prevent ovulation by a similar mechanism to a combined pill because of the high dosage, and the action of the progesterone used. It also has the secondary mechanism of increasing mucus viscosity. As for the rings, implants etc, it depends on the hormones used, but they follow the same basic mechanisms.

It’s kind of surprising that you have so much knowledge on the subject, yet you misspelled estrogen multiple times.

didn’t you look? im from England thats how we spell it in english…if you wasn’t so ignorant and bothered to look you would know why i spelt it “wrong”

It wouldn’t be a big deal if she did misspell it. I don’t see why you felt it was necessary to point that out.

exactly…its not like you can’t understand any of it or im writing in slang. 3 people managed to understand it and there American too.

Also, she is not the only one who spelled that word like that on this post. So, why single her out?