◉ Summary of Use during Lactation:Limited information on the use of estradiol during breastfeeding indicates that the route of administration and dosage form have influences on the amount transferred into breastmilk. Vaginal administration results in measurable amounts in milk, but transdermal patches do not. Maternal doses of up to 200 mcg daily transdermally do not increase estradiol or estriol in breastfed infants or cause any adverse effects in breastfed infants. Vaginal administration results in unpredictable peak times for estradiol in breastmilk, so timing of the dose with respect to breastfeeding is probably not useful.
A case report of inadequate milk production and inadequate infant weight gain was possibly caused by transdermal estradiol initiated on the first day postpartum, but 2 small studies found no such effect when the drug was initiated after lactation was well established.
◉ Effects in Breastfed Infants:A mother who had severe postpartum depression with 2 previous infants was prescribed a transdermal estradiol patch that released 50 mcg daily beginning on day 1 postpartum to prevent recurrence of depression. At 11 days of age, the infant was jaundiced and had gained only 60 grams since birth. With more frequent nursing, weight gain improved, but remained inadequate until day 28 when the estradiol was discontinued. The infant then experienced above average weight gain through day 66 postpartum. The delayed and reduced weight gain was possibly caused by estradiol.
Six nursing mothers received transdermal estradiol as part of a study comparing estradiol to sertraline and placebo for postpartum depression. The mothers received estradiol dosages between 50 and 200 mcg daily (mean 133 mcg daily) at the time of serum level analysis at 4 and 8 weeks of therapy. Four of the 6 infants were exclusively breastfed and the other two were more than 50% breastfed. There was no difference in infant length, weight, and head circumference nor in the average daily gains in any of these parameters between treatments.
A transgender woman took and spironolactone 50 mg twice daily to suppress testosterone, domperidone 10 mg three times daily, increasing to 20 mg four times daily, oral micronized progesterone 200 mg daily and oral estradiol to 8 mg daily and pumped her breasts 6 times daily to induce lactation. After 3 months of treatment, estradiol regimen was changed to a 0.025 mg daily patch and the progesterone dose was lowered to 100 mg daily. Two weeks later, she began exclusively breastfeeding the newborn of her partner. Breastfeeding was exclusive for 6 weeks, during which the infant's growth, development and bowel habits were normal. The patient continued to partially breastfeed the infant for at least 6 months.
◉ Effects on Lactation and Breastmilk:Thirteen women who were 12 weeks postpartum and fully breastfeeding their infants were given a transdermal patch that released 100 mcg of estradiol daily. The average number of breast feeds per day did not change significantly during 3 days of patch application.
Nineteen women who were 6 weeks postpartum, using a barrier contraceptive method and breastfeeding their infants were randomized to transdermal patches that released estradiol 50 mcg daily or placebo patches for 12 weeks. An additional control group received no patches. The number of breast feeds per day decreased in all groups over the course of the study, but there were no important differences among the groups.
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.
