Is Estring Safe in Breastfeeding

I am a breastfeeding mother and i want to know if it is safe to use Estring? Is Estring safe for nursing mother and child? Does Estring extracts into breast milk? Does Estring has any long term or short term side effects on infants? Can Estring influence milk supply or can Estring decrease milk supply in lactating mothers?

A natural Estrogen that is marketed for oral, injection and topical administration (skin and vaginal).On the chemical form of valerate, it is used in association with a progestin as a combined birth-control compound (e.g. Estring + Dienogest) Estring is excreted into breast milk in clinically non-significant amount (Nilson 1978) and no problems have been observed in infants whose mothers were treated (Pinheiro 2016). Plasma levels of these infants were undetectable or very low (Pinheiro 2016). After administration in the form of transdermal patches milk levels have been undetectable (Pinheiro 2016, Perheentupa 2004). Despite these data, an older publication associated the use of transdermal Estring with a case of jaundice and poor weight gain (Ball 1999).There is greater passage to milk when the administration is vaginal. There is evidence (albeit inconsistent) that estrogen-containing pills may decrease milk production, especially during the first few weeks postpartumThey may reduce the protein content of the milk. No problems have been observed in infants whose mothers were treated, except some cases of transient gynecomastia in infants whose mothers were receiving a higher dose than usual. Estrogen exposure in childhood or adolescence, does not influence the subsequent production of milk. The American Academy of Pediatrics states that this medication is usually compatible with breastfeeding.

Limited information on the use of Estring 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 Estring or estriol in breastfed infants or cause any adverse effects in breastfed infants. Vaginal administration results in unpredictable peak times for Estring 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 Estring initiated on the first day postpartum, but 2 small studies found no such effect when the drug was initiated after lactation was well established.

A mother who had severe postpartum depression with 2 previous infants was prescribed a transdermal Estring 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 Estring was discontinued. The infant then experienced above average weight gain through day 66 postpartum. The delayed and reduced weight gain was possibly caused by Estring.[4] Six nursing mothers received transdermal Estring as part of a study comparing Estring to sertraline and placebo for postpartum depression. The mothers received Estring 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.[3]

Thirteen women who were 12 weeks postpartum and fully breastfeeding their infants were given a transdermal patch that released 100 mcg of Estring daily. The average number of breast feeds per day did not change significantly during 3 days of patch application.[5] Nineteen women who were 6 weeks postpartum, using a barrier contraceptive method and breastfeeding their infants were randomized to transdermal patches that released Estring 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.[6] A retrospective cohort study compared 371 women who received high-dose estrogen (either 3 mg of diethylstilbestrol or 150 mcg of ethinyl Estring 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.[7]