This volume contains most of the papers presented at the First International Symposium on The Effect of Prolonged Drug Usage on Fetal Development held at the Beit-Berl Convention Center, Kfar Saba, Israel, on September 14 - 17, 1971. In order to obtain an overview of the effect of drugs on fetal development, it appeared desirable to gather the opinions of noted investigators regarding the goals already achieved and the future potential of prevention of fetal disorders due to drugs. More than one hundred and sixty scientists from fifteen countries participated, and over forty presented data...