Birth Control or No?

[michelleybelle.livejournal.com]

Alright, I was talking with my roommate (who is a bio major) today, and we got on the topic of breast feeding. She mentioned that it was a form of birth control. I thought she just meant that in the case where a woman is breast feeding, she wouldn't have sex and voila - birth control. But no, she says that a woman physically can not get pregnant if she is breast feeding. Now this sounds suspect to me. Does anybody know anything about this?

Comments

[dystatic.livejournal.com]

it has to do with hormones
oh hell i dont remember, this was grade 12 bio...
progesterone is the one that sustains a pregnancy and is needed for lactation
i do believe that the theory is that as long as your body is continuously producing progesterone (for lactation) your thyroid wont produce GnRH (gonadotropin-releasing hormone, which stimulates the production of follical stimulating hormone which starts the whole cycle again)
i think the problem with this is that everything happens in levels..
so if youre hormones get out of wack, or maybe youre just low on projesterone, the whole cycle can start again.
i think in a perfect world, with perfectly working bodies it works, but no one has a perfect working body
its probably not smart to rely on hormones as a form of birth control
http://infertility.about.com/library/ifctr/blfhorm.htm
that link has some info on the reproductive hormones
i wish i had my bio notes i could explain things better.