Babies vary greatly in size and shape. Parents sometimes compare their baby to other babies and worry if she's smaller or larger than other babies at the same age. However, according to KidsHealth, the size of the baby does not necessarily indicate the size the child will ultimately grow to be. As long as the baby exhibits healthy weight gain and growth patterns, there isn't anything to worry about.
Birth Weight
The birth weight of babies depends on the length of the pregnancy, the size of the parents, the mother's health and nutrition during the pregnancy, birth order, whether or not the baby is one of multiples, the baby's health and the baby's gender, according to KidsHealth. Most babies fall within the range of 6 lbs. 2 ounces and 9 lbs. 2 ounces, as long as they are full-term babies.
Normal Growth
Doctors will monitor your baby's growth patterns during well-child visits by plotting her weight and height on a growth chart. Usually there is no concern as long as your baby grows from visit to visit, according to Mayo Clinic emeritus consultant Jay L. Hoecker, M.D. Typically, babies who are breastfed will gain about 4 to 7 ounces per week for the first month, about 1 to 2 lbs. each month for the first six months and 1 lb. a month for the rest of the first year, according to Dr. William Sears, author of more than 40 parenting books. Babies who are fed formula tend to be a bit heavier after the first six months.
Significance
A baby usually reaches double his birth weight by the time he is 4 to 6 months old, and triples it by the time he reaches a year of age, according to the Australian Breastfeeding Association. Babies who are formula-fed tend to retain more water and have a different body fat composition than those that are breastfed, and this accounts for the differences in weight.
Considerations
How you weigh your baby is very important, because you want to be able to accurately compare the weights you get. It is best to use the same scale at the same time of day and wearing similar clothes, or no clothes, each time. Whether the baby has just eaten or just had a bowel movement can also affect the weight, so this needs to be taken into consideration.
Expert Insight
Babies go through different growth stages, so they might stop growing for a short time and then have a growth spurt. This is totally normal and nothing to worry about. There are a few situations that are cause for concern, however. According to the Australian Breastfeeding Association, if your baby loses weight after he is 10 days old and doesn't reach his birth weight again by three weeks of age, if he falls below the third percentile line on the growth chart, if he drops two percentile lines in 56 days when under 5 months old, or within three months if he is over 5 months old and if he gains less than 100 grams per week during his first three months.
