Review: Detrimental effects of alcohol exposure around conception: putative mechanisms

In western countries, alcohol consumption is widespread in women of reproductive age, and in binge quantities. These countries also continue to have high incidences of unplanned pregnancies, with women often reported to cease drinking after discovering their pregnancy. This suggests the early embryo may be highly exposed to the detrimental effects of alcohol during this periconceptional period. The periconception and pre-implantation windows which includes maturation of the oocyte, fertilisation and morphogenesis of the pre-implantation embryo, are particularly sensitive times of development. Within the oviduct and uterus, the embryo is exposed to a unique nutritional environment to facilitate its development, and establish de novo expression of the genome through epigenetic reprogramming. Alcohol has wide-ranging effects on cellular stress, hormonal and nutrient signalling pathways which may affect the development and metabolism of this early embryo. In this review, we summarise the adverse developmental outcomes of early alcohol exposure, prior to implantation in animal models, and discuss potential mechanisms which may occur within the protected oviductal and uterine environment. One interesting candidate, is reduced retinoic acid synthesis, as it is implicated in the control of epigenetic reprogramming and cell lineage commitment, processes which have adverse consequences for the formation of the placenta, and subsequently, fetal programming