By six months of age, birth weight is typically what?

• A. One half of the birth weight.
• B. Birth weight is doubled by six months.
• C. Birth weight is tripled by six months.
• D. Birth weight quadrupled by six months.

Answer: (B)

Infants gain weight rapidly in the first half-year, with the typical pattern showing birth weight doubled by about six months. This reflects the strong caloric intake from breast milk or formula and the body’s growth needs during this period. By around one year, birth weight is usually tripled, and by about two years it’s quadrupled, though there is individual variability. So doubling by six months is the common milestone. The other options would imply too little or too much growth for six months: halving would indicate weight loss, while tripling or quadrupling by six months is not typical.