The placenta plays an essential role in childbirth. It becomes disposable after the baby is born which makes it the only organ in the human body that serves a vital function and then becomes obsolete. It is an extremely complex piece of biological equipment which allows the mother's and the baby's blood to come into very close contact, without mixing, to supply nutrients and oxygen to the baby, and move waste products like carbon dioxide back from baby to mother. Thus, the placenta acts as the lung, kidney and digestive system for the baby. The placenta also plays an important role in hormone production. Human chorionic gonadotropin is produced by the placenta and can be found in the baby's blood as early as 10 days into pregnancy. The placenta is also responsible for the production of other hormones including oestrogen and progesterone and protects the baby from possible infection or from damage by substances found in the environment or used by the mother, such as alcohol, drugs, pollutants and endocrine disrupters. This book presents the reader with a comprehensive, well written and informative collection of chapters written by experts from around the world. It will be a valuable asset for anyone interested in reproduction and pregnancy and wanting to access excellent reviews as well as the most current discussion of the biology and medicine of the placenta.