C₁₈H₂₄O_{2 +} C₂₀H₂₆O₂

Combined oral contraceptive (COC) of estrogen (ethinyl estradiol) and progestogen (norethisterone) in the form of pills for oral use. Daily administration.

Hormonal contraceptives, both combined (COC) and progestogen-only, do not alter the composition of milk, neither in minerals (Mg, Fe, Cu, Ca, P) nor in fats, lactose, proteins or calories. ^{(Urzica 2013, Dórea 2000, 1999 y 1998, Costa 1992)}

No short-term or long-term clinical, physical or psychomotor developmental problems have been observed in infants whose mothers were taking a COC ^{(Lopez 2015, Nilsson 1986)}, except for a few cases published years ago of transient gynecomastia. ^{(Madhavapeddi 1985, Nilsson 1978, Marriq 1974, Curtis 1964)}

No study has found negative effects on breast milk production or infant weight gain when COC are started after the first 2, or better 6, weeks postpartum. ^{(Tepper 2015, Bahamondes 2013, Espey 2012)}

During lactation progestin-only contraceptives are preferable to those combined with estrogen and, in this case, those with a lower dose of estrogen. ^{(CDC 2016, 2013 y 2010, WHO/OMS 2015, Altshuler 2015, Berens 2015, CLM 2012)}

If a COC is taken during lactation, it is advisable not to start it before a month and a half after delivery and monitor milk production through the growth of the infant. ^{(Moretti 2000)}

For the first 4-6 weeks postpartum, non-hormonal methods are the first choice, followed by IUDs and progestogen implants. ^{(Berens 2015, Mwalwanda 2013, Rowe 2013, CLM 2012)}

The American Academy of Pediatrics states that COC are usually compatible with breastfeeding. ^{(AAP 2001)}

ESTRADIOL is excreted into breast milk in clinically insignificant ^{(Nilson 1978)} or null amounts ^{(Pinheiro 2016, Perheentupa 2004)} and no problems have been observed in infants whose mothers were treated. ^{(Reisman 2018, 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)}

Estrogens, alone or associated with progestogens, have been used in the treatment of excess milk production^{(Johnson 2020)} and to suppress lactation ^{(Piya 2004, Balmer 1971)}, although with very little success. ^{(Kaern 1967)}

There is low quality evidence that estrogen-containing pills may decrease milk production or the duration of breastfeeding, especially if given during the first few weeks postpartum and with a daily dose equal to or greater than 30 micrograms (0,03 mg) diarios.^{(WHO 2002, AAP 2001, WHO 1988, Nilsson 1986, Tankeyoon 1984, Díaz 1983, Peralta 1983, Croxatto 1983, Guiloff 1974, Kaern 1967)}

NORETHISTERONE (norethindrone) is a progestin derivative of 19-nortestosterone. 

It is excreted in breast milk in clinically significant amount ^{(Betrabet 1987, Toddywalla 1980, Saxena 1977)} and no problems have been observed in infants whose mothers took it. ^{(WHO 1994, Shaaban 1991, Giner 1976, Karim 1971)}

Plasma levels of these infants were undetectable or very low.^{(Betrabet 1987)}

No alterations have been observed in the amount or composition of breast milk in mothers treated with norethindrone. ^{(Giner 1976)}

See below the information of these related products:

• (Contraceptive combined Estrogen & Progestins) (Fairly safe. Mild or unlikely adverse effects. Compatible under certain circumstances. Follow-up recommended. Read Commentary.)
• Estradiol (Fairly safe. Mild or unlikely adverse effects. Compatible under certain circumstances. Follow-up recommended. Read Commentary.)
• Norethisterone (Safe substance and/or breastfeeding is the best option.)