How Does Your Baby Grow?
By Doris Taha, M.D., and Henry Anhalt, D.O.
Infants spend a lot of time growing during their first year of life.
Normal growth depends on three main things: genetics, nutrition and
hormones. Each time your infant visits the doctor for a well-visit
checkup, she'll be weighed, have her height measured and have her head
circumference calculated, which will all then be compared against a
standard growth chart. This is to help establish a growth pattern, and
also allows your pediatrician to detect any deviations from it which
signal a problem, such as a nutritional deficiency.
Typically, a newborn loses 10 percent of his body weight within the
first week. But by the time he's two weeks old, he should regain or
even exceed his birthweight, gaining about one ounce per day during the
first three months. Between 3 and 6 months, this slows down to about 1
1/4 pounds per months, and then a 1/2 ounce per day between 6 and 12
months. With this rate of growth, your infant should double his birth
weight by 4 to 5 months and triple it by the time he's 1 year old.
Reaching New Heights
Most newborns average length is 20 inches at birth. An infant grows in
length at a rate of 3.5 cm per month in the first 3 months; 2 cm per
month between 3 and 6 months; and 1.2 to 1.5 cm per month between 6
months and 1 year. The infant's length averages 75 cm at 1 year of age.
The Role Genetics Play
Changes in the growth rate are not so unusual during the first two
years of life, and can depend on the size of the parents (i.e., large
infants born to small parents tend to slow their growth, whereas small
infants born to large parents tend to accelerate it during the first
two years of life.) In such cases, the determinant of small size is
genetic and should not raise concerns. In other words, the apple
doesn't fall far from the tree.
Conditions that Hinder Growth
Nutrition is the most important factor that influences growth.
Conditions that might prohibit an infant from getting proper nutrition
- Structural malformations of the face and mouth, including cleft lip and palate.
- Neurologic disorders leading to the inability to suck and swallow normally.
- Gastrointestinal diseases manifesting with vomiting and/or diarrhea.
- Psychosocial problems as in child neglect or disturbed mother-infant relationship.
- Cardiac or respiratory disease where exhaustion and labored breathing may lead to inadequate dietary intake.
is why it's important to pay special attention to symptoms suggesting
illness (including vomiting, diarrhea, feeding difficulties and
respiratory distress), as well as your baby's eating patterns and
In infancy, many children who fail to thrive
show developmental delays and abnormalities of posture. This is why
malnutrition during the critical period of brain growth should be
identified promptly and treated vigorously to minimize central nervous