Most parents experience anxiety when it appears that their baby has not gain enough weight. Many suffer needlessly due to receiving misleading information about average weight gain figures for babies. This article assists parents to better understand their baby’s growth and decide if there is reason for concern.
What is average weight gain?
Every parent wants to be reassured that his or her baby is achieving healthy growth. One way to gain reassurance is to compare baby’s weight gain against the average weight gain achieved by babies of the same age.
The answer to ‘What is average weight gain?’ is complex. The average gain differs between boys and girls; between breast-fed and formula-fed babies; between different ethnic groups; according to the time period the gain occurred; and also varies depending on baby’s age.
Infant weight-for-age percentile charts provide the best example of average weight gain. Average is represented by the 50th percentile curve. The two most frequently used infant weight-for-age percentile charts are:
CDC growth chart
The 2000 CDC infant weight-for-age percentile growth charts are based on U.S. national survey data, and include both breast and formula-fed babies proportional to the feeding method of infant population at the time, which included a larger percentage of formula-fed Caucasian babies.
It’s difficult to tell what is the average gain over a specific time period using a graph. The following table approximates into daily, weekly and monthly figures the 50th percentile curve of male babies. The average weight gain for female babies is marginally less.
*A baby can lose up to 10 percent of body weight after birth and may not regain this for up to two weeks. Weight gain in the first months varies considerably. Note: Babies do not gain weight every day. Growth occurs in spurts.
The Center of Disease Control (CDC) currently recommends that the WHO infant growth charts be used for children from birth to 2 years. However, some health professional still use the CDC charts and quote ‘average’ figures based on these charts.
WHO growth chart
The WHO infant weight-for age percentile charts, released 2006, are based on data on the growth pattern breast-fed babies. The data was collect from 6 countries believed to support optimal growth, including the U.S.
It has long been recognized that the growth patterns of breast- and formula-fed babies differ. The WHO standards establish growth of breast-fed babies as the norm. WHO infant growth charts were developed to prevent breast-fed babies’ growth being compared against the growth pattern of formula-fed babies, as occurs when using CDC charts. Using CDC charts, a breastfed baby’s growth could be mistaken as being poor and feeding strategies employed that lead to an early end to breastfeeding for baby.
The following table approximates into figures the 50th percentile weight gains for male babies. The average weight gain for female babies is marginally less.
*A baby can lose up to 10 percent of body weight after birth and may not regain this for up to two weeks. Note: babies do not gain weight every day. Growth occurs in spurts.
As you can see, the figures in the WHO table are quite different to those in the CDC table. In general, it showed that breast-fed babies tend to gain weight more rapidly in the first 2 to 3 months. And from 6 to 12 months breast-fed babies tend to gain less than formula-fed babies.
What average means
Average weight gain is NOT the minimum amount that every baby should gain.
Average weight gain figures are determined as a result of studies that average the weight gain of thousands of babies of the same age. Average weight gain provides the middle point of a normal weight range for age. This means approximately 50 percent of babies gain more and 50 percent less.
What if baby does not gain average weight?
It may be reassuring that your baby has gained average weight. But what if he hasn’t?
Some health professional cite simplistic figures such as an ounce (30 grams) a day or 5 to ounces (115 to 230 grams) per week as average. While these figures might be average for babies of a particular age group, they are not the average weight gain for all age groups, and so can be misleading. Other health professionals might use a series of figures for different ages. These usually involve a few basic numbers that are easy to remember, for example:
- Birth to 3 months: 5 to 7 ounces or 150 to 200 grams per week.
- 3 to 6 months: 3.5 to 5 ounces or 100 to 150 grams per week.
- 6 to 12 months: 2.5 to 3 ounces or 70 to 90 grams a week.
Note: These figures above are based on CDC average figures, which are primarily based on Caucasian, male, formula-fed babies.
If concerns have been raised because your baby has not gained average weight, the first question you need to ask is - Where do these figures come from? The WHO or CDC chart? Or something else? Does the source reflect the typical growth pattern of babies fed the way your baby is fed, i.e. breast- or formula-fed?
It’s widely accepted that breast-fed babies’ growth represents the biological normal growth pattern for babies, but the fact is formula-fed babies don’t follow the same growth pattern as breast-fed babies. So while its not advisable to compare the growth of breast-fed babies against CDC growth charts, it may be unrealistic to compare the growth of formula-fed babies against WHO growth charts.
Some parents are given figures that are unrealistic and unachievable for a baby of their baby’s age. So, the next question is what age group do the quoted figures represent? As you can see from the tables above, babies don’t continue to gain weight at the same rate as they mature. If the figures you have been given or found on a website are for babies younger than yours, they will be higher than average for babies of your baby’s age.
Even when using figures that match for both feeding method and age, gaining more or less than average doesn’t mean your baby’s growth is poor or extreme. No baby will consistently gain average weight over time. Not even babies who are of average length, i.e. on the 50th percentile curve of an infant growth chart.
Short babies - those whose length falls below the 50th percentile and especially those lower than the 25th percentile for length - born to short parents will likely gain less than average.
Long babies - whose length is above the 50th percentile and in particular over the 75th percentile - born to tall parentsmight gain more. But that’s not a certainty.
Small deviations either side of average are usually insignificant.
Large deviations in either extreme might indicate a problem, but not necessarily so.
Large weight gains are seldom considered to be problematic by parents or health professionals, when in some cases this could indicate that baby is overfeeding - which is a problem that can lead to a number of other baby care problems.
Low gain, plateau or weight loss is usually what parents and health professionals become concerned about. However, in many cases concerns are unfounded. The fact that a baby’s weight gain is low, stagnant or appears like he has lost weight should not be automatically assumed to be a problem or that baby’s not eating enough. There are many false alarms and variations of normal growth that can give the appearance of poor growth or weight loss that need to be assessed.
What to do if you're worried
Avoid jumping to wrong conclusions based on incorrect or insufficient information. Making changes to your infant feeding practices without a full understanding of the situation could make the situation worse. (See Consequence of baby growth mistakes.)
If your baby doesn’t gain average weight or the amount expected, it means further investigation is needed to confirm if there’s a genuine problem or whether concerns stem from lack of understanding – yours or baby’s healthcare professional’s – of the many reasons babies don’t gain as much weight as expected.
Step 1: Look for signs that indicate if baby is well fed. If the signs point to him being well fed, there’s probably nothing wrong with his growth.
Step 3: If you’re still concerned consult with your baby’s healthcare professional. Alternatively, if he/she was the one that raised growth concerns based solely on the fact that your baby didn’t gain average or expected weight, i.e. without asking you questions to assess your baby’s current nutritional state, without considering the possibility of false alarms and normal variations in growth, and without calculating body mass index or weight to length ratio to ascertain whether she is currently overweight, underweight or normal weight - seek a second opinion.
If there is a genuine growth problem, the most common cause of poor growth is underfeeding. And extreme growth is overfeeding. Read our articles on these topics before making changes to your infant feeding practices. To effectively resolve any feeding-related problem, feeding strategies, treatments or therapies must match the cause. There may be steps you can take to prevent underfeeding or overfeeding to occur.
Written by Rowena Bennett.