The advent of assisted conception procedures such as in-vitro fertili sation (IVF) has provided the impetus for exploration of the factors that lead to the establishment of pregnancy. This collection of papers from leading research workers brings together current concepts of the processes which may be of importance in implantation. The complex signals from the embryo to the ovary, endometrium and myometrium are now being revealed through studies in both primates and other mammalian species. This book addresses the interrelationship of pituitary and ovarian hormones in controlling ovulation and the preparation of the intrauterine environment for implantation. Once fertilisation has occurred and trophoblast has formed, the next vital step is the production of materials which signal the presence of the pregnancy to the rest of the body. Trophoblastic proteins and other early-pregnancy factors are prime candidates for this role. Recent studies have emphasised the importance of the intrauterine environment in implantation. Specific secretory products of the endometrium have great potential in this process. The prostaglandins also play an essential part. Immunological adjustments are now considered a condition for the successful establishment of pregnancy. The possible use of immuno therapy in the treatment of recurrent abortion has highlighted interest in this area. The use of immunological techniques for contraception are in their infancy but offer much hope for the future.

A variety of new techniques that promise to revolutionize the clinical management of early pregnancy are fully detailed in this state-of-the-art book. Leading international researchers describe fast-moving topics such as embryo manipulation and the diagnosis of congenital abnormalities. The technology of assisted reproduction has made it possible to study living embryonic material for the first time, which has led to rapid advances in our understanding of the human embryo's early development. For example, study of the embryo in the test tube has pointed to early pregnancy loss as a possible cause of later infertility. Even more important, diagnostic tests using sophisticated techniques of molecular biology can be run on single cells before the embryo is replaced in the uterus. Another area of advance is the diagnosis of congenital abnormalities in the first and second trimesters of pregnancy. Great improvements have been made in the techniques of chorion villus biopsy and ultrasound imaging. A spectrum of simple biochemical tests performed on the mother's blood can greatly improve the detection of Down syndrome and other chromosome defects. Together with other developments in the fields of molecular biology and endocrinology, these new diagnostic techniques are the beginning of a new age in clinical human genetics and embryology.