The purpose of this paper is to provide an overview of our works on the effects of noise during human fetal life. It was found by recording electroplethysmography that babies born of mothers who came to a noisy area around an airport before or during the first five months of pregnancy were little aroused from sleep. Besides, human placental lactogen levels in the serum of expectant mothers exposed to the noise are significantly lower after the thirtli-six week of pregnancy. Thus, noisy environment affects baby 'a birth weight.