- Babies come in all shapes and sizes, with a wide range of normal. Your baby's size is dependent on a number of factors, such as the size of the parents, the type of food baby eats and whether your child is a boy or girl (boys tend to be bigger). When determining is your baby is growing correctly, a pediatrician will consult a growth chart while also taking into consideration whether your baby has met developmental milestones and is generally happy and responsive.
- The main way a pediatrician tracks your baby's growth is through the use of an infant growth chart. Infant growth charts show the statistical distribution of height, weight and head circumference for U.S. babies. The chat plots the highest, lowest and middle-range measurements of growth for a particular age and sex. Your baby's measurements are then charted and compared to other babies of the same age and sex. When your pediatrician explains that your baby's in the "90th percentile" for height, this means that 90 percent of all babies of the same age are shorter, while only 10 percent of U.S. babies are taller. The most important thing doctors check for is a consistent growth pattern, no matter if it's above or below the national average.
- Babies typically grow 1 inch per month in the first six months. From 6 months to 1 year old, they slow down, gaining about ½ of an inch per month. As for weight, babies gain 4 to 7 ounces per week in their first month. After the first month and up to 6 months old, their weight gain slows down and they average 1 to 2 pounds a month. From 6 months to 1 year of age, they gain about 1 pound a month.
- Growth charts aren't always accurate for exclusively breastfed (EBF) babies. Growth charts are formed by looking at a portion of American babies who are mostly formula-fed. EBF babies grow much differently than formula-fed babies. According to Kelly Bonyata, a certified lactation consultant, breastfed babies grow more rapidly than formula-fed babies in the first few months of life and then grow less rapidly from 3 to 12 months of age. A doctor who closely follows growth charts may inadvertently scare a mom by saying her baby isn't gaining enough weight fast enough when actually the baby is doing fine.
- Babies under a year old who don't consistently gain weight for three consecutive months will need further evaluation.
