This article from La Leche League International,Can I get pregnant while nursing?
, provides the 'rules' for the LAM of birth control.
Within that article, there is a link to the original abstract
from August 1993.
I was just reading about LAM from my LLL Breastfeeding Answer Book, which is upstairs and thus I am unable to exactly quote it, so we must rely on my memory. One of the interesting tidbits mentioned in the text is that if a LAM-follower does menstruate before 6 months, it is most often an anovulatory period. After 6 months, it is most often an ovulatory period.
From memory, the frequency of breastfeeding rules are:
* every 4 hours during the day
* every 6 hours during the night
Moms using LAM are to be wary once baby starts 'sleeping through the night,' because that nighttime nursing is vital to stavving off fertility. I am 5 weeks pp and plan on using LAM, so let's HOPE my memory is accurate!
LAM works because every time the infant stimulates the nipple, the hormone prolactin is released...and prolactin negates the effectiveness of estrogen.
Estrogen is required to release an egg, and once the quantity of estrogen in the body rises to level x, the body will ovulate. This is why the frequency of nursing is important.
As I understand it, all day long estrogen is released into the body, and each nursing provides a shot of prolactin to nullify the effects of the estrogen in the body at that time. And the you're back to no estrogen again, 'til it starts accumulating again, and a few hours have passed, and BOOM you need another prolactin shot to balance the warring hormones, so to speak.