At what age should an infant typically double their birth weight?

Infants typically double their birth weight by around 6 months of age. This is an important milestone in growth and development during the first year of life. During these early months, infants experience rapid growth as they are adjusting to feeding outside the womb and starting to use energy for their increasing activity levels. Doubling their birth weight indicates that they are receiving adequate nutrition and developing normally.

Around 3 months, while infants do gain weight, they usually do not reach double their birth weight yet. By 12 months, most infants reach a weight that is about three times their birth weight, so that's too late to signify the milestone of doubling. Similarly, 18 months is well beyond the typical timeframe for this growth marker. Thus, identifying 6 months as the appropriate answer aligns with the established developmental benchmarks for infants.