Growth and development start at conception and continue through adolescence. During conception and the prenatal stage, the genetic makeup and the basic physical structure of the child are determined.

When children enter the toddler years, their physical growth starts to slow down, and they rapidly develop gross motor and language skills. The toddler years are also characterized by the child’s need for autonomy.

conception — the biological process of a sperm fertilizing an egg. toddler years — also characterized by the child’s need for autonomy. phenylketonuria (PKU) — a rare metabolic disorder that can cause intellectual disabilities but is highly treatable with diet modification. high-risk pregnancy — any pregnancy in which there are increased health risks for the pregnant person, the developing fetus, or both.