What is considered mild microcephaly?
Microcephaly is a birth defect in which a baby's head is smaller than expected, compared to babies of the same sex and age. Babies with mild microcephaly often don't have problems other than small head size.
When should I be concerned about my baby's head size?
Pediatricians usually measure head circumference only in children under the age of 2, since the head doesn't grow much after the fontanelles (soft spots) close at around 18 months. Again, head size is mostly genetic — so if you or your partner has a small head, your child may have a petite one too, and vice versa.