Here we uncover the mysteries of the baby as it develops in the womb, discussing how fetal development is controlled. We give insights into aspects of pregnancy not widely known, from the fetus starting to breathe months before it is born, to the question of whether it sleeps – and dreams. We discuss the ways in which information about the mother’s life and her environment affect the baby’s development. Although birth may seem the first major milestone for a baby, we emphasise that many other milestones have been passed before that, inside the womb, out of sight but over which parents can have substantial influence. We give insights into new discoveries about how the organs of the fetal body develop in prediction of the world in which that individual ‘expects’ to live, and what happens when the prediction turns out to be wrong. The idea that the fetus is preparing for life after birth will get the reader thinking about the long-term consequences of the way a fetus develops. Each of us is unique as a result of our development – and nobody is perfect. Our unique development starts from the moment of conception, which introduces the next chapter on sex.