Your baby will triple her birth weight by her first birthday, according to Glade Curtis and Judith Schuler in "Your Baby's First Year." By the time she reaches six months, her weight gain will start to slow down and weight gain will become more irregular due to growth spurts.
While there are guidelines for weight gain, the important focus, according to Curtis and Schuler, is the height-to-weight ratios. This means that your baby's height should keep pace with her weight. According to authors of "The Babycenter Essential Guide to your Baby's First Year," your baby's doctor will view your baby's growth as a pattern. After measuring your baby, the physician will check her previous visit's measurements and compare them to national averages. Doing so helps the doctor determine if your baby is following a healthy growth pattern overall.
Genetics affect growth patterns, also. If members of your family have smaller or larger frames and taller or shorter statures, then your baby may, too.
Curtis and Schuler note that the average weight for a full-term baby is 7 pounds, 2 ounces. Because a baby is born with extra fluid, she will often lose a few ounces after birth, but usually regain the weight during the next week, and reach her birth weight by two weeks.
During the first four weeks of life, your baby will likely gain 2/3 to 1 ounce of weight each day, according to Curtis and Schuler. After the first month, your baby will likely gain 1 to 2 pounds every month until she reaches her sixth month, according to Murray et al. From age six months to 12 months, your baby will gain, on average, 1 pound per month. By the time she reaches her one-year birthday, she will weigh 21 to 26 pounds.
Formula-fed babies tend to gain weight faster than breastfed babies, according to authors of "The Babycenter Essential Guide to your Baby's First Year.". This difference in weight gain is especially evident during months four to six. A breastfed baby may gain 1 pound less than a formula-fed baby during the first year. As physicians expect this difference, it is not a cause for alarm.
William and Martha Sears, in "The Baby Book," note that babies are at risk of obesity not just from genetics, but their diets, too. The Sears' note that many babies are at their chubbiest at around six months of age. Once babies start moving around, they often begin to take on a more lean look. The Sear's remind parents to provide their babies with small portions, once they start eating solid foods, and refill as needed. If bottle-feeding your baby, read their hunger and satiety cues. Babies are good at self-regulating their daily intake needs.
If your baby has not gained enough weight so that she is at least her birth weight by four weeks, or if your baby has been gaining weight, but suddenly stops, your baby's doctor may consider failure to thrive as the cause. A baby with failure to thrive may need nutritional supplements in addition to extra feedings. If breastfeeding, you may need to supplement if the milk supply is not adequate. If this does not remedy the situation, the baby may need to be admitted to the hospital for further evaluation and IV therapy.