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The Normal Weight Ranges for Infants

by Sara Ipatenco, studioD

Babies grow at different rates, but they tend to follow a pattern according to their age. That doesn't mean that your baby will weigh exactly the same as your friend's infant of the same age, however. Your baby's weight at birth plays a large role in her growth pattern, and knowing the normal weight ranges for babies of different ages will help you determine if your infant is on track.


Healthy full-term infants weigh an average of between 5 pounds 8 ounces and 8 pounds 13 ounces, according to the KidsHealth website. Many babies who weigh slightly less or slightly more are completely healthy, as well. In a smaller number of cases, a smaller baby, especially if he's born prematurely, is at an increased risk for certain health problems. Babies that are born larger than average are at a greater risk for low blood sugar, especially if their mothers had gestational diabetes. Once your baby is born, the nurses and doctors will monitor him if he's smaller or larger than average to be sure he doesn't have any special medical needs because of his size.

Four to Seven Months

It's normal for babies to double their birth weight by the time they reach 4 months of age, according to Kids Health. So, if your baby was 6 pounds at birth, she'll weigh about 12 pounds at her 4-month check-up. Normal ranges are between 10 and 18 pounds, according to HealthyChildren.org. She'll continue to gain about 1.25 pounds each month during the next three or four months. However, that doesn't mean that your baby is unhealthy if she doesn't follow this trend. If you and your partner are small, your baby might weigh less than normal, but be completely healthy. If your and your partner are overweight, then your baby might weigh more than normal. If your baby isn't following average trends, her pediatrician will investigate to determine if there's an underlying reason why and what can be done to remedy the situation.

Eight To Twelve Months

By the time your baby reaches his first birthday, he will have tripled his birth weight, according to KidsHealth. According to the growth chart most doctors use, that means your child can weigh anywhere between 18 and 28 pounds. In the four months leading up to your baby's first birthday, his growth will slow down compared to the incredible changes that occurred during the first 6 months of life. Expect your baby's growth to continue being steady so that he remains on the same place on the growth charts. For example, if he's always been in the 50th percentile, he'll likely remain there even if he's not gaining a significant amount of weight. If he drops below or goes above, his pediatrician will keep an eye on him to ensure that he doesn't have a medical problem causing the variation.


In some instances, your baby might be larger or smaller than the averages for her age. For example, premature babies are often smaller than full-term babies of the same age and babies born to large parents can be larger than babies the same age. Certain medical conditions, such as acid reflux, poor latch on a mother's breast, thyroid disorders or celiac disease, can cause growth problems. If you're concerned about your little one's weight, talk with her pediatrician. The doctor will determine the cause of the weight problems so you can work together to develop an effective treatment plan to get your baby back on track.

About the Author

Sara Ipatenco has taught writing, health and nutrition. She started writing in 2007 and has been published in Teaching Tolerance magazine. Ipatenco holds a bachelor's degree and a master's degree in education, both from the University of Denver.

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