Effects of Norethynodrel Combined with Mestranol on the Offspring When Administered During Pregnancy and Lactation in Rats

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Abstract
Rats were treated during pregnancy and lactation with norethynodrel combined with mestranol (Enovid-E) or with mestranol alone to determine the effects of such treatment on the offspring. No genital abnormalities were apparent at birth even with doses up to 1 mg/kg daily. There was no suppression of lactation, as judged by the growth rate of the young, with doses of Enovid-E as high as 0.2 mg/kg; higher doses had only questionable effects. At weaning the male offspring nursed by treated mothers appeared normal. However, the female offspring often had prematurely opened vaginae and incomplete fusion of the edges of the urethral papilla, a condition previously described in the young rats nursed by estrogen-treated mothers. In general, such female young were not fertile and their ovaries were devoid of corpora lutea. The findings were discussed in relation to previous reports on the effects on the offspring of sex steroids administered in the perinatal period.