Infancy is the developmental stage occurring from birth to 12 months during which babies experience rapid changes, including physical growth and brain development. Most newborn babies double their birth weight by the time they are 5 or 6 months old and triple it by their first birthday. An infant’s nervous system – brain, spinal cord and nerves – matures, allowing them better control of the head and limbs, and also enabling them to grasp objects and crawl by their first birthday.

Other milestones healthy infants typically accomplish by their first year include the use of simple gestures like shaking their head and trying to imitate words by making babbling sounds. Although most babies reach certain milestones at similar stages, infancy development can differ. Healthy babies grow and develop at their own pace. Babies who were born prematurely may lag slightly. If they were born a month prematurely, they may reach any given milestone a month later than a full-term baby.

Much intense development occurs during pregnancy, but equally important growth occurs in the first year. The baby begins to breathe at birth, developing the respiratory system. The cardiac system has functioned during prenatal development, but after birth changes occur in the heart so blood is oxygenated and transported throughout the body. The baby begins to feed through the mouth and clears wastes through its own digestive system. The brain and nervous system develop control of body functions and sleep and wake cycles.

In addition to physical development of organs, babies have huge developmental changes in their motor skills, cognitive abilities and psychosocial connections during the first year of life. In each area, there is a wide range of normal development.

Nonetheless, parents should notify their child’s physician if their baby displays signs of possible developmental delays during infancy. These include failure to thrive, not being able to crawl or stand when supported, not searching for objects that are hidden from view, not trying to imitate words or not using gestures such as waving hands or pointing to objects. Possible causes of developmental delays in infants include premature birth, congenital conditions (e.g., fetal alcohol syndrome), mental retardation or lack of adequate nutrition.

To promote infant health and development, pregnant women should receive prenatal care. Research suggests that women who see an obstetrician-gynecologist – a physician who specializes in the female reproductive system and childbirth – regularly during pregnancy have healthier babies, are less likely to deliver prematurely, and are less likely to have other serious problems related to pregnancy.

Another crucial step in promoting healthy infancy development is ensuring that infants get regular check-ups with a physician, preferably a pediatrician. The American Academy of Pediatrics (AAP) recommends well-child visits immediately after birth, then two to four days later, or before going home from the hospital. After that, parents should take their infants for well-child visits at 1, 2, 4, 6, 9 and 12 months of age.

The birth of a baby can be a source of great joy for the entire family. However, because it is a life-changing experience it can be very stressful as parents and other family members adjust to the new addition. Parents can better their chances of adjusting by learning about infancy and healthy development prior to their baby’s birth.

Expecting parents can find information on infancy development on the Internet and in the numerous books available on the subject. Many school districts, hospitals, mental health facilities and community centers offer courses for first-time parents. A physician or mental health professional, such as a licensed family therapist, may be able to provide referrals for parenting courses.