Effects of ethanol exposure on the embryo-fetus: experimental considerations, mechanisms, and the role of prostaglandins

The purpose of this review is to critically examine the effects of ethanol on the embryo-fetus. There has been a tremendous amount of human epidemiological and experimental animal research on the characterization of the anomalies produced by chronic prenatal ethanol exposure and the identification of critical periods of vulnerability and critical amounts of ethanol necessary to produce fetal effects and (or) abnormal development. Few studies have examined the underlying mechanism(s) of the action of ethanol, and even fewer studies have examined the effects of single-dose ethanol exposure on the embryo-fetus. In this review, the current state of knowledge of the effects of chronic use of ethanol on the embryo-fetus is summarized. The primary focus of the review is on the embryonic-fetal effects of acute ethanol exposure, with particular emphasis on the ethanol-induced suppression of fetal breathing movements, as this effect appears to be a very sensitive index of acute exposure of the near-term fetus to ethanol. Factors to be considered in the selection of experimental animals to investigate the mechanism of action of ethanol and to study the acute effects of ethanol are discussed. Postulated mechanisms of action of ethanol on the embryo-fetus are evaluated with a focus on the role of prostaglandins. Finally, future directions in this field of research are proposed.