Embryonic and early fetal loss.

Embryonic and early fetal loss occurs in approximately one out of two pregnancies. Although this rate might appear unreasonably high, it is borne out by several types of studies and further confirmed by careful animal study. It now appears that karyotype deviation is common in early abortuses and probably underlies the high rate of gross abnormality seen in this group. In addition, environmental factors (radiation, smoking, anesthetics, and previous therapeutic abortion) may contribute to this wastage. Study and analysis of the abortus have allowed identification of a number of new embryonic and fetal syndromes. Careful description and classification combined with continued monitoring of abortuses shows promise both as an adjunct to reproductive counseling and as an important defense against teratogenic exposure. It is through this study that the etiology and ultimately the control of preventable pregnancy wastage will be understood and implemented.