One of the ways parents tend to measure the health of their babies is by weight gain. It’s hard not to compare your baby to other infants, but the best way to determine if your baby has healthy weight gain is to measure her against herself. Consistent growth along a curve (with a growth spurt here and there) means that your baby is gaining weight in a healthy manner, according to KidsHealth.

In Utero

Babies start putting on weight during the last five weeks of pregnancy. During this time, weight gain is rapid, as fat is added to the body. Babies born prematurely are often born without this protective layer of fat, and may suffer from complications as a result. Most babies born full-term will have body fat that sits at a healthy 30 percent of total body weight, according to the What to Expect website.

Types

Body shape varies among babies, and the weight gain is different for each of these types. Babies who are long and lean (Dr. Sears calls them “banana babies”) naturally burn off calories very quickly. Apple babies have a pleasingly symmetrical, round shape. Pear babies tend to have lovely chubby legs. Apple and pear babies do not burn off calories as quickly as banana babies. They most often gain weight faster than they grow, so that they are above average in weight but perhaps below average in length. This is perfectly normal.

Time Frame

Most newborns weigh between 6 and 9 lbs. at birth, according to KidsHealth. It is not unusual for newborns to lose some of that weight in the weeks shortly following birth, however. Formula-fed babies lose about 5 percent of their weight during the first week of life, while breastfed babies can lose up to 10 percent. Most babies quickly gain the weight back. During the first year, a healthy baby will just about triple her birth weight, give or take a few pounds.

Considerations

Formula-fed babies tend to gain weight differently than breastfed babies. This does not mean one is healthier than the other. Still, the method of feeding should be taken into account when plotting the baby’s growth on a growth chart, according to AskDrSears.com. Breastfed babies put on an average of between 1 to 2 lbs a month for the first six months of life, and an average of 1 lb during the second six months. Formula-fed babies gain weight faster, starting in the fourth month. At the end of one year, formula-fed babies weigh an average of 1 lb more than breastfed babies.

Warning

Some babies who do not show progress on the growth chart are diagnosed as having a “failure to thrive.” This title is usually given to babies who dip below the third percentile on the growth chart, or who weight 20 percent or more below what is considered a healthy weight for his age, according to BabyCenter. Blood tests or urine tests may be ordered to determine the cause. Feeding problems, such as latching issues in breastfeeding or an allergy to milk, are often the cause. Reflux can also cause babies to spit up before nutrients are absorbed. Once a diagnosis is reached, your doctor can help your baby maintain a healthy weight again.