The mammalian embryo relies on physical connections to its mother to survive. After implantation into the wall of the uterus and before the placenta is established, a structure known as the decidua forms and is key to supporting embryonic development. Defective formation of an effective decidua is thought to be a cause of female infertility. A team of researchers, led by Toru Miyazaki, at the University of Tokyo, Japan, has now determined that the protein DEDD is required for the formation of a functional decidua in mice. The authors therefore suggest that it would be interesting to investigate whether DEDD dysfunction is the cause of infertility in some women.