Is Norethindrone safe while breastfeeding?
Here is what NIH LactMed, the U.S. National Library of Medicine's authority on medicines and breastfeeding, reports about Norethindrone. This is a summary of that source — not our own verdict.
Effects on the breastfed infant
No consistent physical, mental, or radiologic differences have been found in infants whose mothers were using norethindrone enanthate (Norplant).[ 11 , 12 ] Some studies found increased infant weight gain among the infants of treated women.[ 11 , 13 , 14 ] A short-term study of 12 women who received oral norethindrone 350 mcg daily starting 48 hours postpartum found no differences in infant weight gain over 14 days compared to 8 women taking a placebo.[ 15 ]
Effects on milk supply
Studies of varying size and quality on the use of long-acting norethindrone injections (acetate or enanthate) have found that the use of levonorgestrel implants (Norplant or Norplant-2) as a contraceptive beginning at 6 weeks postpartum or later either has no clinically important negative effect on the quality of breastmilk and results in either no effect or an increase in the milk supply and duration of lactation.[ 11 - 14 ] In one study, women who received the implant at 6 days postpartum, a transient decrease in milk protein occurred 2 weeks after implant insertion. A decrease in milk phosphorus content was also observed between 2 and 4 months after implant insertion in this group and at 3 months postpartum, the early insertion group had a higher rate of supplementation.[ 16 ] In another study, women given norethindrone enanthate depot injection less than 48 hours postpartum were 2.5 to 3 times more likely to have postpartum depression at 6 weeks postpartum. No differences were seen at 1 and 12 weeks postpartum.[ 17 ] A short-term study of 12 women who received oral norethindrone 350 mcg daily starting 48 hours postpartum found no differences in milk production or milk composition over 14 days compared to 8 women taking a placebo.[ 15 ] One small, nonrandomized study found that oral norethindrone 350 mcg daily decreased the quantity and quality (lower protein, lipids and calcium) compared to controls who received nonhormonal contraception.[ 18 ] In a nonrandomized, nonblinded study comparing women who were breastfeeding at discharge, 102 postpartum women received depot medroxyprogesterone acetate (dosage not stated) in the early postpartum period (average 51.9 hours postpartum; range 6.25 to 132 hours), 181 received another progestin-only contraceptive and 138 used nonhormonal contraception. No differences in breastfeeding rates were seen at 2 and 6 weeks, but women receiving any hormonal contraceptive were breastfeeding at a lower rate (72.1% vs 77.6%) at 4 week
Levels in milk
Maternal Levels. Five women with well-established lactation (exact time postpartum not stated) were given an oral dose of 350 mcg of norethindrone daily. Breastmilk levels were measured several times on the first day of treatment. Peak milk levels occurred at 2 or 4 hours after the dose in various individuals. Average milk levels were 0.747 mcg/L at 2 hours after the dose; 0.747 mcg/L at 4 hours; 0.396 mcg/L at 8 hours; 0.253 mcg/L at 12 hours; and, 0.174 mcg/L at 12 hours after the dose.[ 8 ] Milk norethindrone levels were measured in 4 women after daily ingestion of oral norethindrone 350 mcg started after 3 months postpartum. Peak milk norethindrone levels in the range of 0.4 to 0.5 mcg/L occurred between 1 and 3 hours after the dose and dropped slowly over the 6-hour study interval to about 0.15 to 0.4 mcg/L.[ 9 ] At 6 to 20 weeks postpartum, 15 women received a single tablet of a combination oral contraceptive containing a dose of 3 mg of norethindrone. At 2 to 2.5 hours after the dose, a foremilk sample was taken. The mothers breastfed their infants and then a hindmilk sample was taken. The two samples were pooled for assay. Milk levels averaged 2.4 mcg/L (range 0.9 to 5.5 mcg/L).[ 10 ] Infant Levels. At 6 to 20 weeks postpartum, 15 women received a single tablet of a combination oral contraceptive containing a dose of 3 mg of norethindrone. At 2 to 2.5 hours after the dose the mothers breastfed their infants; infant serum samples were taken 1.5 to 2 hours later at about 4 hours after the maternal dose. Infant serum levels averaged 0.19 mcg/L which was 0.8% of peak maternal serum levels drawn at 2 to 2.5 hours after the dose.[ 10 ]
Alternatives LactMed lists
Source: NIH LactMed (National Library of Medicine).
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.