Infants grow and develop at an astonishing rate. It is normal for parents to become concerned about their babies' development and want to make sure they are on the right track. While there are guidelines to consider concerning your baby's physical development, you should discuss any questions or concerns with your pediatrician since every baby develops differently.
Growth
Infants typically lose between five and 10 percent of their birth weight immediately after birth, according to the National Institutes of Health. By the time your baby is two weeks old, he should start gaining weight. Most babies double their birth weight between four and six months of age, and weight gain should slow down during the second half of the first year. The World Health Organization has standardized graphs and tables showing the relationship between a baby's length in centimeters and age in weeks or months. These tables depict percentiles, meaning if your baby is in the 75th percentile, he is taller than 75 percent of infants his age.
Reflexes
Newborns show primitive reflexes, such as the Babinski reflex in which the baby's toes spread out when you stroke the sole of her foot, and the Moro reflex which causes the baby to extend her arms and then pull them back in toward her chest when startled. Newborns will also turn their heads and try to suckle when their cheeks are stroked, grasp a finger placed in their palms and take quick steps when placed with their feet down on a hard surface, provided their weight is supported. These primitive reflexes usually subside between three and four months of age, according to the National Institutes of Health.
Dexterity
Most infants begin using their hands and feet to swipe at objects by the time they are four months old, though most have not yet developed the coordination to grasp things that are not placed directly in their hands. By five to six months of age, babies often begin to grasp objects with their palm and fingers, though most do not use their thumbs yet. Babies continue to develop dexterity throughout the first year of life until they can pick up small objects and begin to place objects together, such as stacking blocks or lining up pieces of food.
Mobility
Many infants develop sufficient neck strength to sit up with support by the time they are a few months old. By the time they are six months old, many healthy babies can sit up without support for several seconds and roll from their backs to their stomachs. Once on their stomachs, infants typically prepare for crawling by learning to push up on their arms to support their upper bodies. While babies begin crawling at different times, most begin at between six and nine months of age. Once an infant masters crawling, he will usually begin to pull himself into a standing position within a few months. Between six and nine months of age, most infants are able to sit without support for long periods of time. Many babies begin taking steps and walking shortly before their first birthday.
Considerations
It is important to remember that there are no definitive rules for your infant's physical growth. Premature babies often reach physical milestones later in life. While delayed growth is often nothing to be concerned about, it is important to take your baby to her pediatrician for regular visits, especially if you have concerns about her growth. In some cases, delayed growth can indicate illness, infection or poor nutrition.
