What Should My Baby's Height and Weight Be?

Growth charts are tools your pediatrician can use to keep track of your child's physical growth. During each checkup, the doctor will measure your baby’s length, weight, and head circumference. The doctor can then compare the measurements for your baby to a chart of national averages for infants of the same age and sex. The result is that the doctor will be able to tell you what percentile your baby is in when compared to averages for babies around the nation. For example, if your doctor tells you your 4-month-old is in the 86th percentile for weight, that means 86 percent of the two-month-olds in your country weigh less, and that 14 percent weigh more. A baby that is at the 50th percentile in either height or weight is right at the national average.

Typically, parents seem to worry quite a bit about these percentages, and that worrying is usually needlessly blown out of proportion. There are many factors that come into play when determining where your baby’s statistics will fall in the percentile chart. It is very important to remember that no two babies are the same and that every child, due to body chemistry, heredity, diet, and many other factors will grow at their own pace. Some babies will have growth spurts right from the start and others will take a bit longer to begin major growth periods. These measurements, charts, and percentile points are merely guides for a doctor to help in assessing your baby’s growth.

In addition to the measurements that your pediatrician will take during regularly scheduled doctor visits, you may also want to track your baby’s growth at home. Keep in mind that the measurements you take at home may or may not be as accurate as the measurements your doctor takes, but they can provide a certain degree of insight into the growth of your baby and many new parents have found it to be a fascinating way to participate in the parenting process.

Here are some tips that can help you, as inquisitive parents, track your baby’s growth at home using commercially available scales and other measuring devices.

If baby is too small to stand upright on the scale, you can try using this procedure:

• With your baby in your arms, step onto a standard bathroom scale.
• Make note of the weight displayed on the scale and write it down on a piece of paper.
• Put your baby down and step onto the scale alone this time.
• Make note of the weight displayed and subtract this number from the combined weight of you and your baby. The resulting number is your baby’s weight.

To measure your baby’s length all you need to do is lay her down on a flat surface (her changing table is a great place for this task) and stretch a measuring tape from head to toes.

For the measuring of head circumference all you need to do is wrap the measuring tape around your baby’s head. You should wrap the measuring tape just above your baby’s eyebrows, so the tape falls right at the top of the ears. What you are trying to measure is the point around his head that has the largest circumference.

When taking your baby to the doctor, your pediatrician will perform more accurate measurements. Pediatricians do the “baby measuring thing” on a daily basis and will be able to achieve a much more accurate result than you will at home. This is due to the fact that they are accustomed to the things babies do that can result in an inaccurate measurement and they have very accurate measuring tools made specifically for the purpose of measuring the characteristics of babies, such as proper baby scales equipped with cradles. Your doctor will most likely take measurements several times during one visit and average the results together to ensure accuracy and to compensate for any discrepancies that may arise. It is crucial for the doctor’s measurements to be as accurate as possible because a discrepancy of as little as a few millimeters in length or a few grams in weight can make a difference where your baby falls on the charts. Since the results of these measurements may determine changes to your baby’s diet, and other possible changes to how your baby is fed and treated during her first year, it is important that these results are as accurate as possible.

Your pediatrician will measure the following characteristics of your baby:

Weight: After calibrating the scale the doctor or nurse will place your completely naked baby on a baby scale. There are electronic and traditional beam-type versions of the baby scale, but most will typically have the same type of baby holding stainless steel cradle. After your child is able to stand on her own, your pediatrician will most likely use a standard upright scale.

Length: Like weighing, until your baby is able to stand up on his own, your doctor will perform the height/length measurements with your baby lying down. Your doctor may use a tape measure, much like you use at home, or may utilize a special “baby-measuring device”, which consists of a headboard and movable footboard to obtain the most accurate results possible.

Head circumference: This measurement will be taken in almost the same way you did at home. The doctor will take the measurement at the point where the head is at its largest circumference, right above the ears and around to the back of the head where the neck meets the cranium. Usually the pediatrician will record this measurement to the nearest 0.3 cm (1/8th of an inch).

The head is different from other parts of the body in that the brain is not fully formed at the time of birth and therefore the head will continue to grow during baby’s first year. Baby’s head is a particular point of concern for the doctor because a head that is growing too rapidly can be a sign of hydrocephalus (water on the brain) and a head that is growing too slowly can be indicative of nutritional or developmental problems. Regardless, you shouldn’t be too concerned if your baby’s head appears a bit disproportional compared to the rest of her body, as this is completely normal for the first year of life.

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