I must say I don't think I know what the effect, presumably on
breastfeeding, would do.  Probably nothing, as progesterone is high
during pregnancy anyway.  The placenta's contribution will disappear
after the birth of the baby, and so there will be a drop in progesterone
after the birth.  One hopes that that will allow the alveolar cells of
breast to become sensitized to prolactin and all would work well.

Jack Newman, MD, FRCPC