Okay, since we are back on this thread, I'd like to chew on some of it a
little more.  For the most part, we know that breastfeeding during pregnancy
does not cause miscarriage or premature labor. We add caveats for high-risk
pregnancies and histories of premature delivery, and ask if sex has been
banned.

BUT-- what has been said in defense of breastfeeding has to do with oxytocin
receptors. I remember reading that they do not actually proliferate fully
until the end of pregnancy, and therefore there shouldn't be enough of them
to react to oxytocin release during breastfeeding or orgasm enough to cause
full labor. Heck, although nipple stim can be used to try to start a labor,
look how often it *doesn't* work!

But then on the other hand,  I start thinking about miscarriages, which occur
early in pregnancy and require oxytocin to contract and pass the fetus.  How
does the concept of lots/not alot of receptors during pregnancy apply here?
Do the receptors proliferate in response to the body's signal to miscarry
first? Or were they already available in sufficient numbers? Understanding
this in conjunction with the above might help us to articulate the answer to
the issue of breastfeeding during pregnancy better than citing studies based
on outcomes of breastfeeding behavior during pregnancy. I like to know *why*,
and not just that it *is*!

I don't remember where I read the stuff on receptors, so I can't go back and
dig further into this. I would love to kick this around a bit on lactnet, and
if someone has more info on this physiological aspect, please toss it in!

-Lisa Marasco, BA, IBCLC
Santa Maria, CA