Behavioral tests in monkey infants exposed embryonically to an oral contraceptive

The behavior of rhesus monkey infants exposed to high levels (20 to 100 X the human therapeutic dosage) of an estrogen-progesterone contraceptive (Norlestrin) during embryogenesis was compared to that of untreated controls. No serious deficiencies in regulation of activity, motor maturity, manual dexterity or discrimination learning were recorded in the 3 to 5 month old infants. In addition, age appropriate sex-differentiated behavior was observed in social groups of treated infants at 5 and 11 months of age. On the basis of this information it seems unlikely that accidental use of birth control pills during early pregnancy will seriously affect behavioral competence of offspring during infancy.