Key milestones in prenatal development include the formation of structures to support growth in the first two weeks, the development of the head, eyes, nose, ears and mouth between 3-8 weeks, and the completion of the physical structure and development of body systems from 9 weeks until birth. Newborns develop gross motor skills like sitting and crawling, fine motor skills such as holding a spoon, and sensory, language and social skills in their first year. Parents can support development by singing, reading, cuddling, and encouraging play to help children succeed in school and life.