Risk Factor: XM
Class: Hormones/ Progestogens

Contents of this page:
Fetal Risk Summary
Breast Feeding Summary

Fetal Risk Summary

Norethynodrel is a progestogen derived from 19-nortestosterone. It is used in oral contraceptive agents and hormonal pregnancy tests (no longer available in the United States). Masculinization of the female infant has been associated with norethynodrel (1,2). The Collaborative Perinatal Project monitored 866 mother-child pairs with 1st trimester exposure to progestational agents (including 154 with exposure to norethynodrel) (3, pp. 389, 391). Fetuses exposed to norethynodrel were not at an increased risk for malformation. However, an increase in the expected frequency of cardiovascular defects and hypospadias was observed for progestational agents as a group (3, p. 394; 4). Re-evaluation of these data in terms of timing of exposure, vaginal bleeding in early pregnancy, and previous maternal obstetric history, however, failed to support an association between female sex hormones and cardiac malformations (5). An earlier study also failed to find any relationship with nongenital malformations (1). One investigator observed three infants, exposed to norethynodrel and mestranol during the 1st trimester, who had congenital defects, including atrial and ventricular septal defects (one infant), hypospadias (one infant), and inguinal hernias (two infants) (6). The relationship between the anomalies and the exposure to the hormones is unknown.

Breast Feeding Summary

Norethynodrel exhibits a dose-dependent suppression of lactation (7). Lower infant weight gain, decreased milk production, and decreased composition of nitrogen and protein content of human milk have been associated with similar synthetic progestogens and estrogen products (see Norethindrone, Mestranol, Ethinyl Estradiol, Oral Contraceptives) (8,9 and 10). The magnitude of these changes is low. However, the changes in milk production and composition may be of nutritional importance in malnourished mothers. If breast feeding is desired, the lowest dose of oral contraceptives should be chosen. Monitoring of infant weight gain and the possible need for nutritional supplementation should be considered. The American Academy of Pediatrics considers norethynodrel to be compatible with breast feeding (11).



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