Progesterone

Excerpt

Because of the low reported levels of progesterone in breastmilk, even with the high-dose products, amounts ingested by the infant are small and would not be expected to cause any adverse effects in breastfed infants. The progesterone vaginal ring available in some countries produces maternal blood levels that are lower than those of ovulating women.[1] Most studies indicate that progesterone is not detrimental to milk production or duration of nursing.[2,3] No special precautions appear to be required.

In Russia, a progesterone gel (Progestogel - Besins Healthcare; not available in the US) has been used topically as a one-time application to the breasts to treat postpartum breast engorgement when more conservative measures have failed.[4] A subsequent study failed to detect any decrease in breast hardness 20 minutes after application of progesterone gel in mothers with engorgement.[5] The safety and efficacy of this use have not been well studied and the manufacturer of Progestogel recommends avoiding its use during lactation.