From conception to birth
This chapter explores what is known about the development in utero in the first, second and third trimesters. It offers a very simplified version of what happens between conception and birth. The second trimester covers months four, five and six. At the beginning of this trimester the tiny foetus has her own fingerprints and her teeth are beginning to develop. There is evidence that she is already moving the muscles in her face to show facial expressions. During the seventh month the wrinkly foetus begins to add layers of fat, and the eyes, which now have eyelashes, begin to open. As the next month starts the photoreceptors in the eyes begin to be able to distinguish light from dark. Only after birth will vision improve so that the infant can see colours and learn to focus. Developments are taking place in the ears too so that the foetus can differentiate high from low sounds.