Breastfeeding, Weight Gain and Growth Charts

A baby’s weight can be a big source of stress for breastfeeding mothers. Is my baby gaining too little or too much? Are they on the right percentile? Am I making enough milk? Often, these concerns stem from parents, and even health care providers, not having a good understanding of what is normal when it comes to babies and weight.

So what is normal? Well, to start with, it is normal for babies to lose some weight after birth. Peak weight loss usually happens on day three (just before mom’s milk “comes in”). Weight loss in hospital is often a big concern, and unfortunately, often a reason for breastfed babies being unnecessarily supplemented with formula. Most hospitals use the measurement of 7% loss from birth weight as an indicator of a problem. The latest research however is giving us new insight into normal newborn weight loss. Dr. Joy Noel-Weiss recently completed a research study looking at newborn weight loss and how that weight loss is affected by IV fluids given to mom during labour. Her findings confirmed what many in the lactation community have thought for some time. IV fluids can artificially inflate a baby’s birth weight. Her study found that IV fluids given to mom during labour and delivery, particularly in the two hours immediately prior to birth, have an impact on how much weight a baby loses after birth. All of that extra fluid has to go somewhere, and some of it goes to baby. After a baby is born and gets rid of the extra fluid, it can look like that baby has lost too much weight. One of the recommendations of the study is that all babies be weighed at 24hrs to allow babies to get rid of any extra fluids they may have in their system, and to use the 24hr weight to calculate weight loss/gain rather than birth weight.

In terms, of weight gain, a healthy term newborn should regain their birth weight by about 7-10 days. A healthy newborn baby who is transferring milk well, is a baby who is growing and gaining weight (after about day 3). If your baby isn’t gaining, or is gaining very slowly, it’s a red flag that something isn’t quite right and breastfeeding needs to be assessed. The first course of action should always be to figure out what is causing the slow weight gain. Whether it’s an issue with mom’s milk production or a problem with baby’s ability to transfer milk effectively, the cause of the problem needs to be determined by someone knowledgeable about breastfeeding. In the first few days in hospital, if your baby is not nursing well and weight gain is a concern, then constant skin-to-skin contact and frequent hand expression and spoon feeding of colostrum are the best approach. If you are being pressured to give formula, you can ask for more time and then get help from an IBCLC.

Once breastfeeding is established, we expect babies to gain at a rate of about 5-7 oz per week (close to an ounce per day), for about the first 3 months. Between months 3-12, weight gain tends to slow down. It is normal for the rate of weight gain to slow down, but it is not normal for weight gain to stop completely or for babies to lose weight. The average breastfed baby doubles their birth weight by about 5-6 months, and at 1 year, they typically weigh 2.5 times their birth weight.

The Centers for Disease Control and Prevention (CDC) and the Canadian Pediatric Society (CPS) both recommend that children’s growth be plotted on the new World Health Organization (WHO) growth charts. The WHO charts, unlike the old CDC charts, are based on the growth of babies under biologically normal conditions (breastfeeding, mothers who don’t smoke etc). When looking at a child’s growth, it is important to be comparing their growth with the biological norm.

For many parents (and health care providers!) growth charts can be a source of great confusion and misunderstanding. When you visit your child’s doctor, their weight is usually plotted on a weight for age growth chart. These charts are used to compare your child to others of the same gender and age. If (for example) your baby’s weight falls on the 25th percentile, it means that statistically speaking, 25% of all babies are that weight or below. Or, to look at it the other way, that 75% of all babies are above that weight. It is very important to understand that the percentile itself is NOT an indicator of health. A baby on the 97th percentile is not healthier than a baby on the 3rd percentile, they just weigh more. Someone has to fall in the 97th percentile, and someone has to fall in the third. What is important is whether or not your child is following their own curve. It is also very important to understand that the 50th percentile does not equal normal or healthiest weight.  The 50th percentile simply means that 50% of all babies are that weight or below. Parents should never be instructed to supplement with formula simply because their breastfed baby is following the 3rd percentile or reduce feedings because their baby is on the 97th percentile. That is NOT how growth charts are meant to be used.

Growth charts are screening tools, not diagnostic tools. This means that if a child is not following the expected pattern according to where they are on the chart, then the doctor needs to look closer to see if something else might be going on. It does not automatically mean that there is a problem.  If a doctor has concerns about a child’s growth then that doctor needs to be looking closely at all aspects of that child’s growth and development. There are several different types of charts available from the World Health Organization, and the weight for length charts or BMI for age charts provide a more accurate picture of an individual child’s growth than the the weight for age ones do.

Weight is only one indicator of growth and should never be looked at in isolation. It is necessary to look at the big picture. The most important thing for parents (and health care providers) to remember is  look at your baby, not just the scale. If your baby is alert and happy, content after feeding, pooping, peeing, meeting developmental milestones, feeling heavier, and outgrowing clothes and diapers, then everything is good (look how many other factors besides weight can tell you that your baby is thriving on your milk!).

Obese 9 month olds?

Several news stories appeared yesterday, based on new research that suggests that almost one third of 9 month old babies are obese (along with 34% of 2 year olds). I haven’t been able to access the original study yet, but according to this news story: “The researchers classified the babies’ weights based on CDC growth charts, which compare a baby’s growth to a standardized growth curve. Kids in the 95th percentile of weight were categorized as “obese,” while kids in the 85th to 95th percentile were counted as “at-risk,” similar to the adult category of “overweight,”.

I see a problem with this. The researchers were using the CDC growth charts when even the CDC itself recommends that the World Health Organization (WHO) growth charts should be used for children ages 0-2. The WHO charts, unlike the CDC charts, are based on the growth of babies under biologically normal conditions (breastfeeding, mother’s who don’t smoke etc). When looking at a child’s growth, it is important to be comparing to the biological norm, not a cultural one (if they had used the WHO charts they likely would have found even higher numbers of “obese” babies!).

The report goes on to say: “The find hints at an unfortunate pattern: Kids who start out heavier end up heavier. Of kids who were normal weight at 9 months old, 75 percent were still normal weight at 2 years. But kids who were at-risk at nine months had only a 50 percent chance of being normal weight at age 2. More than 28 percent of at-risk kids ended up obese by their second birthday.”

Another problem: what is a “normal weight” for a baby? Weight for age growth charts compare a child’s weight to other children of the same age, which really is not very useful. Is your baby healthier than mine because he weighs more or less than mine does? Of course not. All babies are different and someone has to be in the lowest percentile, just like someone has to be in the highest.

The 50th percentile on a growth chart does not equal “normal” weight. It simply means that statistically speaking, 1/2 of all babies of the same age will weigh more, and 1/2 will weigh less. Isolated points on a growth chart have little meaning. What is important is whether or not your not your child is following his/her own curve. If your child falls on the 75th percentile, then he should continue to follow that line on the chart. If your baby falls on the 5th percentile, and is following that curve, then your baby is growing appropriately. A baby on a lower percentile isn’t any more or less healthy than a baby on a higher percentile.

I am curious how the researchers decided that babies who fell in the 95th percentile would be classified as “obese”, and those falling in the 85th-95th would be classified as “at risk”.  Obesity in adults is classified according to Body Mass Index (BMI), not weight. It is not clear from the news story which growth charts the researchers were using in the study (weight for age, weight for length or BMI for age). The type of chart used makes a big difference to how the results should be interpreted.

Childhood obesity is certainly a serious issue that needs to be addressed, but I worry that news stories like these will cause parents to worry unnecessarily about their baby’s weight. Not having a proper understanding of how growth charts work and how they should be used, can lead to parents (and even health care providers!) making changes to a baby’s diet that are usually not in the best interest of the baby. Parents being told to supplement breastfeeding with formula because their baby is on the 3rd percentile and therefore “too small” or being told to restrict feedings or give water between feedings because their baby is “too big” are getting bad advice (and yes, I’ve heard both from parents that I’ve worked with!). Growth patterns can vary widely among young children. Some start out very long and lean and slowly put more weight on, and others start out shorter and heavier and gradually grow into their weight. Labeling a baby as “obese” at 9 months old when most babies haven’t even started walking yet seems absurd.