Is Ethinyl Estradiol safe while breastfeeding?

Effects on the breastfed infant

Published information was not found as of the revision date on the effects of ethinyl estradiol alone on breastfed infants. However, case reports exist of breast enlargement in the infants of mothers taking combination oral contraceptives that contained ethinyl estradiol or its prodrug, mestranol.[ 1 , 4 , 5 ]

Effects on milk supply

Published information was not found as of the revision date on the effects of ethinyl estradiol alone on milk production. However, numerous studies on combination contraceptives containing ethinyl estradiol or its prodrug mestranol indicate that doses of 30 mcg daily or greater might interfere with lactation.[ 6 - 11 ] One study that used a contraceptive containing 10 mcg of ethinyl estradiol found no effect on lactation.[ 12 ] 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.[ 13 ] In a small study on breastfeeding women who were 6 weeks to 6 months postpartum, participants completed a questionnaire on their breastfeeding. Women who were receiving contraception with a vaginal ring containing ethinyl estradiol 15 mcg and etonogestrel 120 mcg daily (NuvaRing) were compared to women who were receiving an oral contraceptive containing either ethinyl estradiol 20 mcg plus desogestrel 150 mcg daily, desogestrel 75 mcg daily alone, and breastfeeding women taking no hormonal contraception. The vaginal ring was associated with up to 20% reduced milk volume when comparing two timepoints before and after combines hormonal contraception introduction. The vaginal rings, but not oral contraceptives, were correlated with impairment in 5 of 12 breastfeeding variables: breastfeeding interval, self-expressed milk volume, use of milk substitutes, number of night-feedings, and number of full diapers.[ 14 ]

Levels in milk

Maternal Levels. Four women who were fully nursing their infants were given a contraceptive containing ethinyl estradiol 50 mcg and megestrol acetate 4 mg beginning at 2 months postpartum. Another 4 women who were 6 to 18 months postpartum were given a single dose of 500 mcg of ethinyl estradiol. After 10 days of therapy, ethinyl estradiol was undetectable ( 50 ng/L) in the milk of women who received the 50 mcg dose at several times after the dose. In those who receive 500 mcg, peak milk levels usually were found in the 3-hour sample although the peak was found in the 7-hour sample in one. Peak milk levels ranged from about 170 to 300 ng/L; levels dropped rapidly and were usually undetectable by 23 hours after the dose. Based on the higher dose, the authors estimated that a fully breastfed infant whose mother was taking 50 mcg of ethinyl estradiol daily would receive a dose of about 10 ng daily.[ 1 ] Milk was collected and pooled from 2 groups of women who were taking ethinyl estradiol 100 mcg 3 times daily either immediately postpartum or after 1 to 6 months postpartum. Milk samples were collected 2 hours after the dose. Pooled milk was bioassayed for estrogenic activity and compared with the milk from lactating mothers taking no exogenous estrogens whose milk was collected at various times postpartum. No estrogenic activity was detected ( 10 ng/80 mL of pooled milk [ 0.125 mcg/L]) from women taking ethinyl estradiol above background estrogenic activity found in control colostrum.[ 2 ] A study measured ethinyl estradiol in the milk of 14 breastfeeding women: 6 using combined oral contraceptives (15, 20, or 30 mcg daily of ethinyl estradiol), 7 using a vaginal ring (15 mcg daily of ethinyl estradiol), and 1 using a transdermal patch (35 mcg daily of ethinyl estradiol). A control group of 8 breastfeeding women not using hormonal contraceptives was also included. Ethinyl estradiol was undetectable ( 3.5 mcg/L) in all of the women.[ 3 ] Infant Levels. Relevant publishe

Alternatives LactMed lists

• Estradiol