Physical growth: 3 to 12 months

At about three months of age your baby's growth will begin to slow down. If the growth rate did not slow down, your new baby would be the size of an adult by age two years.

Most babies will double their birth weight by five to six months of age and triple it by 12 months of age.

In the third to sixth month of age a baby's weight usually increases about 1 1/3 pounds (0.6 kilogram) each month. His or her length increases about one-half inch (1.25 centimeters) and the head circumference about 0.4 inches (1.00 centimeter) per month.

Growth measurements

Many clinics take growth measurements using the metric system. For help converting metric measurements to the British/American system, see clinical growth charts by the National Center for Health Statistics.