Water relations of early embryogenesis

Attention is drawn to the changes in maternal serum osmolality that accompany ovulation, fertilization and early embryogenesis, and the possible significance of those changes is discussed in relation to the sequence of development. From these considerations it is tentatively concluded that maternal hydration influences all stages of early development, and that transient derangement of maternal body fluid regulation could, therefore, be a significant factor in the aetiology of fetal malformations.