Can I take progesterone while pregnant or breastfeeding?

E. Pregnancy Progesterone capsules should not be used during pregnancy. Reproductive studies have been performed in mice at doses up to 9 times the human oral dose, in rats at doses up to 44 times the human oral dose, in rabbits at a dose of 10 mcg/day delivered locally within the uterus by an implanted device, in guinea pigs at doses of approximately one-half the human oral dose and in rhesus monkeys at doses approximately the human dose, all based on body surface area, and have revealed little or no evidence of impaired fertility or harm to the fetus due to progesterone.

Prescribing label, section “Pregnancy”: PROGESTERONE (oral), REMEDYREPACK INC. Label on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.

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 outside the US produces maternal blood levels that are lower than those of ovulating women. Expert opinion holds that the risks of progestin-only contraceptive products usually are acceptable for nursing mothers at any time postpartum.[1,2]

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.[3] A subsequent study failed to detect any decrease in breast hardness 20 minutes after application of progesterone gel in mothers with engorgement.[4] The safety and efficacy of this use have not been well studied and the manufacturer of Progestogel recommends avoiding its use during lactation.

“Summary of Use during Lactation”, LactMed record “Progesterone” (LM470), quoted verbatim. Everything LactMed reports about Progesterone while breastfeeding.

Nursing Mothers Detectable amounts of progesterone have been identified in the milk of nursing mothers. The effect of this on the nursing infant has not been determined.

Prescribing label, section “Nursing Mothers”: PROGESTERONE (vaginal), Sun Pharmaceutical Industries, Inc. Label on DailyMed. Quoted verbatim; US labels are written for US prescribers and patients.

This quote is from the vaginal formulation label.