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Mestranol / norethindrone Pregnancy and Breastfeeding Warnings

Mestranol / norethindrone is also known as: Genora 1/50, Necon 1/50, Nelova 1/50 M, Norethin 1/50 M, Norinyl 1+50, Ortho-Novum 1/50

Mestranol / norethindrone Pregnancy Warnings

Animal studies have not been reported. Epidemiological data have failed to reveal an increased risk of birth defects following maternal exposure to oral contraceptives prior to conception or when taken inadvertently during early pregnancy. There are no controlled data in human pregnancy.

AU TGA pregnancy category B3: Drugs which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.

US FDA pregnancy category X: Studies in animals or humans have demonstrated fetal abnormalities and/or there is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience, and the risks involved in use of the drug in pregnant women clearly outweigh potential benefits.

Use is contraindicated

AU TGA pregnancy category: B3
US FDA pregnancy category: X

-Discontinue use if pregnancy is confirmed.
-Pregnancy should be ruled out for any patient who misses 2 consecutive periods; the possibility of pregnancy should be considered after the first missed period for patients who have not taken pills as prescribed.

See references

Mestranol / norethindrone Breastfeeding Warnings

Not recommended

Excreted into human milk: Yes

-This drug is not recommended for the first 3 weeks postpartum and possibly longer due to risks for venous thromboembolism.
-Oral contraceptives given in the postpartum period may interfere with lactation by decreasing the quantity and quality of breast milk.
-When possible, nursing mothers should be advised to use other forms of contraception until the child is completely weaned.

Jaundice and breast enlargement have been reported in nursing infants of mothers using oral contraceptives during breastfeeding. Combined oral contraceptives have been known to reduce milk production and change the composition of breast milk. When possible, nursing mothers should not use combined hormonal contraceptives during the fourth week postpartum due to the potential to adversely affect the milk supply.

The World Health Organization suggests that combined oral contraceptives should not be used in nursing mothers before 42 days postpartum and the disadvantages of using the method generally outweigh the advantages between 6 weeks and 6 months postpartum.

See references

References for pregnancy information

  1. Cerner Multum, Inc. "Australian Product Information." O 0
  2. "Product Information. Necon 1/50 (mestranol-norethindrone)." Watson Pharmaceuticals (2019):

References for breastfeeding information

  1. Cerner Multum, Inc. "Australian Product Information." O 0
  2. United States National Library of Medicine "Toxnet. Toxicology Data Network." (2013):
  3. "Product Information. Necon 1/50 (mestranol-norethindrone)." Watson Pharmaceuticals (2019):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.