Development and growth

1. How long does it take for the birth length to double? For the birth weight to triple?
2. How many fontanels are present at birth and when do they close?
3. How many ossification centers are present in an infant? What is the first bone to calcify in utero?
4. What is the earliest marker of abnormal neurological maturation?

Answers:
1. Birth length doubles in four years. Weight triples in one year, quadruples in two years.
2. Six fontanels (anterior, posterior, 2 sphenoid, 2 mastoid). Anterior normally closes at 10-14 mo, posterior at 4 months.
3. 5 ossification centers: distal femur, proximal tibia, calcaneus, talus, cuboid. Clavicle is the first to calcify in utero, during fifth fetal week.
4. Obligatory or persistent primitive reflexes.