Microcephaly means a baby’s head is much smaller than expected for age and sex. The difference is usually clear at birth or shows up during the first two years of life. The most visible sign is the head size itself. When measured, the distance around the skull falls below the third percentile on standard growth charts. A small head can make the face look larger and the back of the head flatter. Fontanelles—the soft spots—may close early, and forehead slope can seem pronounced. Development often slows. Sitting, crawling, or walking may arrive late. Some children need extra help with speech... Learn more