A new study into the early stages of embryo development could lead to a deeper understanding of why many pregnancies fail, researchers say. Between seven and 14 days after an egg is fertilised, scientists discovered that a group of cells outside the embryo called the hypoblast triggers the development of the embryo’s head-to-tail body axis — the initial step in the formation of the human body. Very little is currently known about human embryo development once it has implanted into the uterus because of ethical restrictions on the use of human embryos in research. Why do you think pregnancies’ fails nowadays ?

