Is Estradiol Cypionate safe while breastfeeding?
Here is what LactMed, the Drugs and Lactation Database published by the U.S. National Institute of Child Health and Human Development (NICHD), reports about Estradiol Cypionate. The text below is quoted from that source — it is not our own verdict.
Summary of use during breastfeeding
Estradiol cypionate has not been studied during breastfeeding. However, a similar drug, estradiol valerate, has been used to suppress lactation. Estradiol cypionate should be avoided in mothers wishing to breastfeed, especially if started before the milk supply is well established at about 6 weeks postpartum. The decrease in milk supply can happen over the first few days of estrogen exposure.[1]
Effects on the breastfed infant
A telephone follow-up of 16 women taking short-term high dose estradiol valerate found no adverse effects on appetite or growth in their breastfed infants at a median follow-up age of 13 months. The median age of the infant at the start of therapy was 2 months (range 1.5 to 4 months) and the median daily dose was 2 mg (range 1 to 4 mg).[4]
Effects on milk supply
Another injection ester form of estradiol, estradiol valerate was previously used therapeutically to suppress lactation, usually in combination with testosterone.[5-7]
A retrospective cohort study compared 371 women who received high-dose estrogen (either 3 mg of diethylstilbestrol or 150 mcg of ethinyl estradiol daily) during adolescence for adult height reduction to 409 women who did not receive estrogen. No difference in breastfeeding duration was found between the two groups, indicating that high-dose estrogen during adolescence has no effect on later breastfeeding.[8]
Eight women taking estradiol valerate or estradiol hemihydrate in a median daily dose of 2 mg (range 1 to 4 mg) were followed up by telephone. The median time postpartum at the start of therapy was 2 months (range 1.5 to 4 months). The mean breastfeeding duration was 8.5 months. However, 8 of the women experienced a decrease in milk supply and 3 required supplementation with milk production not returning in these three.[4]
Levels in milk
Maternal Levels. Relevant published information on estradiol cypionate was not found as of the revision date. However, estradiol appears in breastmilk in small amounts after administration by other routes.[2,3]
Infant Levels. Relevant published information was not found as of the revision date.
Alternatives LactMed lists
Source: Drugs and Lactation Database (LactMed), National Institute of Child Health and Human Development (NICHD), via NCBI Bookshelf, record “Estradiol Cypionate” (LM852). LactMed on NCBI Bookshelf. LactMed is a registered trademark of the U.S. Department of Health and Human Services.
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.