Some further thoughts on the progesterone topic --  Keep in mind that "natural" or "bio-identical" or "micronized progesterone" are not the same as the progestins typically used in oral and injectable hormonal contraceptives. The progestins used are forms of chemically altered progesterone so that they will be metabolized more slowly for daily or other dosing schedules, which is also good for pharmaceutical companies because they become patented property.  Examples are norethindrone, norgestimate, norgestrel, and levonorgestrel as oral forms and medroxyprogesterone as an injectable form -- all synthetic and having a similar effect and all with differing side effects, which is why oral contraceptives can cause bloating, moodiness, etc., etc. --- I wanted to point out this difference between progesterone and progestins because too often these terms are used interchangeably and they are two different things, which is why "natural progesterone" has such a better side effect profile and can be so much better tolerated for those who need to take this type of hormone for whatever reason.  (By the way progesterone is the hormone that helps support pregnancy to maintain the endometrial lining for the growing embryo and fetus.)  It also helps mature and differentiate the developing ductal and alveolar cells during pregnancy to prepare for lactation.  I'm not sure about the effects on the lactation process itself or the amount that would influence increase or decrease of lactation, itself.  But when oral progesterone is taken (as in Prometrium), it has to be absorbed from the gut and make a first pass through the liver where up to 85 or 90% is metabolized so that one might consider a 100 mg. dose becoming equivalent to 10 to 15 mg. when used as a vaginal suppository or cream or as a dermal cream. (Lee, John R., What Your Doctor May Not Tell You About Menopause, Warner Books, 1996.)
Just further food for thought I wanted to share.  It would be interesting to know what amounts actually absorbed would affect lactation.  (Also, keep in mind when a progestin containing IUD is used it, too, will be directly absorbed without a first liver pass.  It would therefore be more potent than the same dose orally.)  Also, I was taught that depomedroxyprogesterone (the 12 week injectable contraceptive) was supposed to be compatible with breastfeeding and could even had the side effect galactorrhea.
My .02 for today, please share your thoughts, too.  Ellie Lentner

 

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