Perinatal Genetics: Diagnosis and Treatment brings together the proceedings of the 15 Annual New York State Health Department Birth Defects Symposium held on September 30-October 1, 1984 in Albany, New York. The symposium provided a forum for clarifying and rationalizing certain aspects of diagnosis and treatment of perinatal genetic birth defects such as fragile X syndrome, phenylketonuria, and hypothyroidism. Comprised of 17 chapters, this book begins with an epidemiological review of very early pregnancy loss, focusing on fertilization and implantation; the probability of loss between fertilization and implantation (on about the sixth day), and between implantation and the 14th day (the first day of the expected next period in a non-pregnant woman); and the contribution of chromosomal errors in the sperm, ovum, and zygote to early reproductive loss. The reader is then introduced to cytogenetic abnormalities in spontaneous abortions of recognized conceptions; repetitive spontaneous abortion; and prenatal genetic diagnosis by chorionic villus sampling. Subsequent chapters explore prenatal treatment of biochemical disorders; in vitro fertilization and embryo transfer; and moral issues concerning third trimester pregnancy terminations. This monograph will appeal to perinatologists, neonatologists, obstetricians, pediatricians, and geneticists and should also serve as a useful guide for health professionals who provide care to pregnant women and their newborns.