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Baby Weight Gain During the First Year

Katlyn Joy |26, January 2014


It's one of the first facts you learn and share about baby; how much he or she weighed. What's considered low birth weight, and when is a big baby a bad thing? How about in the months to come; what's the normal growth pattern? Does Mom or Dad's size influence this pattern in any way?

birth weight

According to the National Institutes of Health, the average range for a newborn's weight is 5 1/2 pounds at the low end and a maximum of 8.75 pounds.

Babies who fall within this range have the lowest incidence of death and disease. Babies who are larger at birth than average have an increased risk of birth injury and may have low blood sugar as newborns. Typically, larger babies can be attributed to gestational diabetes or a pregnancy that went beyond normal gestational age. Infants of low birth weight are typically, although not always, premature. Such babies are at risk for developing infection, having immature lungs, and having developmental issues later. Other problems that may result in lowered birth weight include placental abnormalities, substance abuse or health conditions of the mother. It's not uncommon to be a low birth weight baby as 1 in 12 US newborns fall into this category. Very low birth weight babies are those weighing under 3 pounds, 5 ounces and have a higher risk of complications.

However, genetics do play a role in baby's weight. Larger parents tend to produce larger children, while those of smaller stature can have similarly built offspring. Other issues can play a role such as boys are often bigger at birth than girls, and first born babies are usually smaller than their younger siblings.

Newborn Weight

Most newborns lose weight in the first couple weeks of life. How much depends on the individual baby, the health, and whether the baby is breastfed or formula fed. In general, a breastfed baby will lose 7 to 10 percent of their total weight but regain it by week 3. A formula fed infant will lose more in the range of 5 percent.

A premature infant or baby born with special health issues may take a bit longer to regain that newborn weight loss.

General Growth Trends in Baby's First Year

In general, a baby will double his or her birth weight by 5 months of age, and will triple it by the first birthday.

A rule of thumb according to the Mayo Clinic is that baby will add about 5 to 7 ounces a week between birth and 6 months, and add 3 to 5 ounces a week from 6 months to 1 year. Of course, every baby is unique and there are growth spurts and quieter times in every baby's life.

What's important is that overall baby keeps growing at a predictable rate, as seen in the baby's well baby visits with the pediatrician or family physician. Baby may be at the higher or lower end of the curves, but should grow in a consistent pattern.

The growth charts commonly used in the US as well as in most of the world were developed by the World Health Organization in 2006. These charts show what a child ages newborn to age 2 should measure in at, rather than compiling data from any specific group or time period as to what children did weigh in at. These standards are set in what the group estimates a healthy breastfed infant will weigh, acknowledging that a formula fed baby will gain weight more rapidly beginning at about the three month mark.

Reasons for Concern

Usually your physician would pick up on any aberrations in a child's growth tracking, but you may have concerns about how a baby is growing. Some actual reasons for concern would include if baby refuses feedings for more than a brief period, seems to not be gaining and is fussy following feedings, is lethargic or doesn't seem to be wetting or soiling diapers as often as expected for age. Of course, anytime something "doesn't seem right," to the parents, it's a reason to seek medical advice. Always trust your instincts as a parent and realize there are no stupid questions when it comes to baby's health.

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