Drug Levels and Effects:

Summary of Use during Lactation:

Norethynodrel is only available in the United States in combination oral contraceptive products. Based on the available evidence, expert opinion holds that nonhormonal methods are preferred during breastfeeding and progestin-only contraceptive are preferred over combined oral contraceptives in breastfeeding women, especially during the first 4 weeks postpartum. For further information, consult the record entitled, "Contraceptives, Oral, Combined."

Drug Levels:

Norethynodrel is a prodrug that is rapidly converted to norethindrone in the body.[1]

Maternal Levels.

In one old study using a nonspecific radiolabeling assay technique, 2 women were found to excrete 0.0044% and 0.13% of an administered dose (not weight-adjusted) of norethynodrel into breastmilk.[2]

In another study using radioactive labeled norethynodrel, 4 women who were between days 4 and 6 postpartum excreted an average of 1.1% (range 0.45 to 1.52%) of a dose (not weight-adjusted) into breastmilk.[3]

Infant Levels.

Relevant published information was not found as of the revision date.

Effects in Breastfed Infants:

Abnormal breast enlargement was reported in a 3-week-old male breastfed infant whose mother was taking an oral contraceptive containing norethynodrel 25 mg and mestranol 100 mcg.[4] The contraceptive was the probable cause of breast enlargement, but most likely theestrogencomponent mestranol rather than norethynodrel caused the effect.

Possible Effects on Lactation:

Relevant published information was not found as of the revision date. However, progestins such as norethynodrel are not considered to suppress lactation.

Alternate Drugs to Consider:

Etonogestrel,Levonorgestrel,Medroxyprogesterone Acetate,Norethindrone


1. Orme ML, Back DJ, Breckenridge AM. Clinical pharmacokinetics of oral contraceptive steroids. Clin Pharmacokinet. 1983;8:95-136. PMID:6342899
2. Pincus G, Bialy G et al. Radioactivity in the milk of subjects receiving radioactive 19-norsteroids. Nature. 1966;212:924-5. PMID:6012386
3. Laumas KR, Malkani PK et al. Radioactivity in the breast milk of lactating women after oral administration of 3H-norethynodrel. Am J Obstet Gynecol. 1967;98:411-3. PMID:5630224
4. Curtis EM. Oral-contraceptive feminization of a normal male infant. Obstet Gynecol. 1964;23:295-6. PMID:14117345

Substance Identification:

Substance Name:


CAS Registry Number:


Drug Class:

  • Contraceptive Agents, Female

  • Contraceptives, Oral, Synthetic

  • Administrative Information:

    LactMed Record Number:


    Last Revision Date:

    Disclaimer:Information presented in this database is not meant as a substitute for professional judgment. You should consult your healthcare provider for breastfeeding advice related to your particular situation. The U.S. government does not warrant or assume any liability or responsibility for the accuracy or completeness of the information on this Site.