In experiments on rats it was found that fenibut (50 mg/kg, 1/20 of LD50) during a single and repeated administration in the fetus period of pregnancy does not exert any negative effect on the maternal organism, the growth and development of the fetus. Seduxen administered in a dose of 50 mg/kg (1/80 of LD50) alone and in combination with fenibut was shown to decrease the female body weight gain and to disturb the fetus development. Following a single administration on the 17th day of pregnancy, the effect was poorly pronounced.