A child presents at a well-child visit. Prenatal and past medical histories are unremarkable. The examination is normal. The child can smile socially. Assuming normal growth and development, at what point is the milestone of smiling socially achieved by 50-90% of children?

A. 2 months
B. 6 months
C. 1 month
D. 9 months

Social smiling is a developmental milestone achieved by 50-90% of children at 2 months of age. It signifies the infant's social engagement and interaction with their environment. It is part of a series of milestones that mark an infant's rapid growth and development in the first year of life.

Explanation:

The milestone of smiling socially is achieved by 50-90% of children at around 2 months of age. This developmental milestone is an important part of infancy, a period characterized by rapid growth and development. Infants generally exhibit this form of social engagement as they respond with smiles to those who engage their positive attention. By 2 months, the social smile becomes a significant aspect of an infant's interaction with their caregivers and environment.

It is noted that infancy is a period of most rapid growth after birth, faster even than during puberty. By the end of the first year, the average baby has grown significantly both in length and weight, and developmental milestones such as sitting alone, which most babies achieve around 7 months, require both coordination and muscle strength.

Concerns about a child's development, especially if they are showing delays in several milestones, should be addressed with a pediatrician. This can allow for early intervention if necessary. Recognizing and responding to these milestones is critical for monitoring a child's growth and development.