Fetal Risk Summary is a brief review of the literature concerning the drug. The intent of the Summary is to provide clinicians and others with sufficient data to counsel patients and to arrive at conclusions on the riskbenefit ratio a particular drug poses for the fetus. The molecular weights of most drugs have been included help determine if a drug can reach the embryo or fetus value, by itself, may not predict the amount of transfer The major determi the drug concentration in the embryo or fetus is the blood concentration of in the mother. Other important factors include placental blood flow, the pla area available for transfer(i.e., correlated to the gestational age). binding, and amount of ionization of the drug at phys- pH