How does my baby grow and develop in the first year?

The first 12 months may be the most dynamic period of life. Dramatic changes are taking place in all areas of growth and development, which include:

• Physical development. Most babies double their birth weight by gaining an average of 0.5 oz to 1 oz every day for the first 6 months of life. Birth weight usually triples somewhere between 9 and 12 months of age. By 12 months of age, most babies have grown a total of about 10 in. in length since birth. Head circumference usually increases about 0.25 in. to 0.5 in. per month.
• Cognitive development. This is the process by which babies develop the abilities to learn and remember. Babies begin to recognize and interact with loved ones and start to understand that people and objects still exist even when they are out of sight (object permanence).
• Emotional and social development. In a loving environment, babies easily bond to their parents. In the first month, newborns express emotion mainly by crying and grimacing or displaying an alert and bright face. By about 4 months, they learn to smile, coo, and move their arms around when excited. By 5 months, babies show a clear preference for a loved one. In the following months, "separation protest" and "stranger anxiety" are two of the ways babies demonstrate this growing attachment. A close bond provides a foundation for future relationships: babies learn from their parents how to love and how to trust.
• Language development. Babies' brains are very open to learning, and they quickly absorb the language around them. By about 3 to 6 weeks, babies develop a different crying sound to indicate a specific need (such as hunger or discomfort). By around 2 months of age, they begin to interact with caregivers by cooing and smiling, which proceeds to babbling and chuckling within about 6 months. Also by 6 months, most babies have learned all of the basic and distinct sounds of their native language.¹ By the first year most babies can say a few words, like "mama" or "dada," and can understand many more.
• Sensory and motor development. A baby's movements become more controlled and deliberate as the newborn reflexes fade. Although seemingly stiff at times, a baby will be limber and coordinated enough in 6 months to suck his or her toes and strong enough to sit with light support. By 10 months, many babies can stand, although they may need support.

When are routine medical visits needed?

Routine checkups, or well baby visits, should occur after the first month at 2, 4, 6, 9, and 12 months of age. During these visits, your health professional examines your baby for signs of normal growth and development. You will be asked about whether your baby is reaching expected developmental milestones. Immunizations are also given according to the standard schedule.