Over the past few decades technological advances in transcriptomics, proteomics, metabolomics, and glycomics, along with the ability to selectively knockout genes of interest, have greatly advanced our understanding of the maternal-conceptus interactions that are essential for the establishment and maintenance of a successful pregnancy. This knowledge provides the basis for new research endeavors to address infertility, embryonic loss and recurrent abortion in humans, captive wild animals and important farm species. This book brings together current reviews from leading experts to address the diversity of mechanisms by which species establish and maintain pregnancy. Implantation in rodents, dogs, pigs, cattle, sheep, horses, primates, humans and embryonic diapause in wild species are discussed. The reviews provide readers with the latest knowledge on the role of the endometrial steroid receptors, adhesion factors, cytokines, interferons, steroids, prostaglandins, growth factors and immune cells involved in the regulation of conceptus development.