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Average Baby Weight: What to Know


Average Baby Weight: A Guide to Your Baby’s Weight

The average baby weight of most babies in the first year is between 5 pounds, 8 ounces and 8 pounds, 12 ounces. If your baby is under-weight or over-weight, you don’t need to worry as average baby weight also depends on factors such as genetics, gender, and size of a new-born. In fact, your pediatrician should be able to detect any anomalies if there is any abnormal change in weight.

Weight is an important measure of growth, it’s important to keep an eye on the weight in the first twelve months. At this stage of the lifecycle, most pediatricians keep a record of weight, length, and head-size, which they share with parents.

According to WHO, World Health Organization, the average baby weight can also differ depending on the region of childbirth; therefore, it may not be feasible to compare baby weight in America against babies born in Asia or Africa. The American Academy of Pediatrics suggests that an average baby born in the United States weights around 3.45 kg.

From Newborn to First Year

After four and half month of birth, the average baby weight doubles compared to the first month, which means that a male baby will weigh approximately 7 kg, while a female baby will weigh around 6.6 kg.

As the child begins to grow, the average difference between a male and a female also becomes evident. For instance, a six-month-old male baby will weigh as much as 7.8 kg compared to 7.1 kg for females.

From six months to the first birthday, the average difference in baby mass of male and female mostly remains constant at 0.7 kg. When the child turns one-year-old, 50 percentile weight for male babies is 10.3 kg compared to 9.5 kg for 50 percentile weight for female babies.

Parents should understand that these figures show an average weight derived from a very large sample of new-born in the United States. Depending on your baby’s physical characteristics, these numbers should only offer a general guideline for understanding a typical weight. If your child is over-weight or under-weight, it does not mean that the baby is not healthy.

How to understand the Weight Chart

Almost every pediatrician in the United States will use a CDC chart to evaluate the development of a baby. The CDC chart provides a graphical interface that can be used to compare the average baby weight against the length of the baby. For instance, if your baby weights 4.3 kg in the first month, it means that 50 percent of babies are over the weight of your baby and 50 percent are below the weight of your baby, at that particular age.

In fact, CDC chart offers a very easy-to-interpret interface that also provides a clear understanding of the percentile range. If the percentile range of your baby suggests 40 percent, it means that 60 percent of babies are over the weight of your baby and 40 percent are under the weight of your baby.

The CDC chart is mostly used by pediatricians to observe an unusual weight. For parents, it means that they should only be cautious if the pediatrician thinks that the weight of the child requires extreme care. In addition to observing anomalies, CDC chart is also used to view growth patterns. If your baby is in the 25th percentile in the first few months, your doctor will work with you to increase the weight to around 50th percentile, and vice versa.

Weight Anomalies

Some parents are overly concerned about the weight of babies during their first month of birth. However, it should be noted that the weight of a baby may change abruptly during the first six weeks, which indicates a normal development cycle.

You need to understand that nearly all babies lose 7 to 10 ounces of weight within a few days of the delivery. The loss of weight is a result of losing extra fluids in their bodies. Once the fluids are removed, it doesn’t take much time for the babies to gain the weight they removed within a few days. As a result, this constant weight change during the first week of childbirth should not concern a parent.

During the first month of life, the average baby weight increases 1 to 2 pounds on a daily basis. Sometimes the increase in weight is more pronounced during specific intervals. For instance, average baby weight also increases rapidly after the 3rd and 6th week. As a result, you should not worry about rapid development. In fact, it will be very naïve of you to constantly check the weight of your baby because weight changes are not constant in the first few months.

The early stage of the growth spurt is also associated with different baby moods. During these growth spurts, in the 3rd and 6th week, you may notice that the baby is getting fussier. Other changes to the mood may include signs of cluster feeding where babies are prone to breastfeed more often in irregular intervals. There will also be signs of uneven sleep cycles; hence, parents should be ready for some sleep deprivation and anxiety.

After the growth spurt, average baby weight increases abruptly compared to previous weeks. It means that you will also require a larger size of clothes and diapers. After the second month and up to half a year, most boys will earn more weight compared to girls. By the end of four and a half month, the weights will most likely double the first-month average weight.

Health Concerns

Following are some of the important reasons that prevent babies from gaining weight:

  • Babies have difficulty breastfeeding or suckling milk
  • They do not get required daily calories of food
  • The diet is deficient in calcium
  • Babies are allergic to milk and yogurt
  • They have a birth defect, which prevents weight gain

Average Baby Weight for Premature Babies

Any baby born before the 39 week gestation period is considered a premature birth. Depending on the date of birth, the weight of the baby may be considerably less than a normal baby born after 39 weeks. A baby born in the 27th week of gestation is often weaker than a baby born in the 34th week of gestation.
Irrespective of the date of premature birth, pediatricians consider a baby weighing between 1.6 kg and 2.6 kg as low weight. A normal baby weights around 3.45 kg on birth, which is almost one to two kg more than premature birth. It’s not uncommon for premature babies to weight 1.5 kg because they are born many weeks prior to the actual birth date.

Premature babies are kept under surveillance in a neonatal intensive care unit before they can be allowed to go home with their parents. During the time, they are given milk through a bottle or by a tube, depending on their condition. Under perfect conditions and health, a premature baby will gain weight quickly in the first month compared to other babies.

Can a premature baby gain weight?

Usually, doctors will allow premature babies to go home once they gain weight at the higher end of the average baby weight for premature infants. At the time, a mother may still need to feed the baby using a bottle because they don’t develop the sucking reflex until the 32nd week.

A premature baby is as healthy as any other baby. The only difference is the special care that premature babies require to catch up with other children. A premature baby will take up to a year to gain the same weight as other babies. In some circumstances, the catching up of weight continues until the second year.


Irrespective of premature or normal delivery, doctors will evaluate the average baby weight starting from the first month of normal childbirth. For parents with premature babies, it means that their pediatrician will compare their babies with other babies that had a normal delivery. Evaluating everyone on the same scale helps doctors to accelerate the growth of premature babies so that they can quickly gain health on par with other children.

Overall, the average baby weight depends on a variety of different factors that include genetics, nutrition during pregnancy, lifestyle, gender, birth orders, and baby’s health. Therefore, you don’t need to concern yourself with trivial issues related to the weight of babies. If everything seems normal, your pediatrician will help you make suitable lifestyle changes to help the baby gain ideal weight.

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