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32 Percent of 9-Month-Olds Are Obese or "at Risk," Large Study Says

By Heather Turgeon |

child obesity and growth chart

Too much of a good thing?

We’ve heard plenty of child obesity statistics in recent years — for example, the CDC says that obesity in kids has more than tripled since the 1980′s. But a large study published last week suggests that the problem may begin with babies as young as nine months old.

The researchers looked at data from almost 9,000 nine-month-olds and 7,500 two-year-olds from the Early Childhood Longitudinal Study-Birth Cohort — a nationally representative sample of kids born in 2001. They considered babies and toddlers between the 85th and 95th percentile to be “at risk”, and those over the 95th percentile to be obese (this is the CDC’s definition).

At nine months, 32% of babies were over the 85th percentile, and 34% were above that mark when they reached two.

There’s nothing more delicious than a chubby baby, and like me I’m sure lots of moms and dads bristle at the term obesity being applied to our littlest munchkins.

But here’s why we should pay attention to this study:

The measurements took into consideration both height and weight together — so a long healthy baby wouldn’t be lumped into the overweight category.

Of course it’s “normal” for a baby to be in the 95the percentile for weight — 5 percent of the population should be there, to be exact. But in this study, 17 percent were over the 95th. And likewise, 15 percent of the population should be over the 85th percentile, whereas the study found 32 percent to be there.

What are growth charts anyway? Well, the CDC’s height-weight charts are the most commonly used (and the ones used in this study as well). They don’t tell us what ideal heights and weights are, they describe the population at a given point in time. The most recent CDC charts are based on a large population of children across the country, mainly from the 1980′s and 90′s.

So according to this data, the number of heavy infants and toddlers has grown considerably in recent decades. And since childhood weight is related to adult weight, there’s no ignoring that a trend towards extra pounds could be starting earlier than preschool.

I have to add that the CDC charts aren’t considered the ideal chart for reference — the World Health Organization charts are the gold standard, because they’re based on a population of primarily breastfed infants. Even the CDC recommends using the WHO charts for children 0-2 years. Babies tend to measure higher on these charts compared to the CDC ones, because formula fed babies gain more weight on average after three months of age.

Just to head off an argument I hear every time this issue is raised: if your baby is in the 95 percentile it doesn’t mean it’s a problem (as I said, 5 percent were there at the time the charts were formed). The problem isn’t heavy babies, it’s the fact that there are more and more of them every year that matters.

image: flickr/caterina

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About Heather Turgeon


Heather Turgeon

Heather Turgeon is currently writing the book The Happy Sleeper (Penguin, 2014). She's a therapist-turned-writer who authors the Science of Kids column for Babble. A northeasterner at heart, Heather lives in Los Angeles with her husband and two little ones. Read bio and latest posts → Read Heather's latest posts →

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16 thoughts on “32 Percent of 9-Month-Olds Are Obese or "at Risk," Large Study Says

  1. Sarah says:

    I don’t understand this statement: “They considered babies and toddlers between the 85th and 95th percentile to be “at risk”, and those over the 95th percentile to be obese” and how it correlates with this: “The measurements took into consideration both height and weight together”

    Do they look at babies above the 85th percentile in weight? or do they look at a fraction of height percentile over weight percentile? If it is a fraction, is it babies above the 85th percent of the fraction? (1 being normal – 2 standard deviations being obese?)

    It would seem that a baby in the 75th percentile in weight but the 25th in height would be “obese” compared to a baby in the 90th percentile in weight, and 95th percentile in height. It seems from the second statement that that is what they are looking at, but the first statement seems to contradict this.

  2. heatherturgeon says:

    sarah: i took it to mean the fraction – as you said, the weight over height measurement. so it would be the kids between the 85th and 95th percentile of weight compared to height that are at risk, and so on.

  3. Rosana says:

    My kids have always being at the 95% percentile but the pediatrician has never been concerned because they are proportionate. Therefore, I think kids should be considered at risk by their pediatrician which is the doctor that has seen them since birth.

  4. IrishCream says:

    Any doctor can tell if they’re “proportionate.” That’s what the authors of this study did by looking at height as well as weight.

  5. mbaker says:

    I have mixed feelings about this. On the one hand, I am concerned about the obesity epidemic in our country. On the other hand, my son who was a chunky baby measured above 90th% on all 3 measurements pretty consistently even though he was breastfed. He’s almost 4 now and because he’s active and we’ve fed him a healthy, varied diet since he started solids he’s now a tall, lanky preschooler. I wonder what the study’s experts would say is his likelihood of adult obesity.

  6. Angela says:

    At nine months most babies eat only breastmilk or formula and small amounts of baby food. Are people really loading babies up on sugar and junk foods? The moms I know definitely don’t.

  7. Joy says:

    Angela, I think instead is that as the percentage of infants who are breastfed declines, coupled with it being statistically more likely that formula fed infants are gaining more weight than breastfed infants, the concern is with the overfeeding with formula.

  8. heatherturgeon says:

    Joy and Angela: the other factor is maternal weight gain in pregnancy, which has been rising over the years.

  9. Jessie says:

    Are you possibly conflating charts here? The BMI chart referred to in the study is not the same as the WHO or CDC growth charts used in the pediatrician’s office to track infant growth.

  10. heatherturgeon says:

    hi jesse: what bmi chart are you referring to? the data in this study (the height and weight measurements) were compared to the CDC’s growth charts.

  11. Rosana says:

    Mmmmm, I know any doctor can tell that. My point is that if a mom has any doubts about her baby being at risk or not, to talk to the baby’s pediatrician. Some people read these things and inmediately think that their baby has a problem, well, they need to know if not by the person most capable of telling them.

  12. Stacie says:

    Am I missing something here?

    Don’t “percentiles” refer to how your baby compares to others–if, say, he’s at the 85th percentile for weight, he’s heavier than 84% of boys his age and lighter than 15% of the boys his age? (Or maybe 85% and 14%?)

    Anyhow…how can 32% of babies be bigger than 85% of babies?

  13. heatherturgeon says:

    32% of babies in the sample (born in 2001) were above the 85th percentile (based on data from the 1960′s to the 1990′s). in other words, more babies and toddlers are heavier now than they were when the growth charts were designed. does that make sense? thanks for the question!

  14. Leah Beah says:

    Having now had two babies who transitioned to formula around the 4-month mark, I can definitely see how we could be “overfeeding.” With breastmilk it’s matched to the baby’s appetite but I could see how a few extra ounces could get into a baby feeding from a bottle. And over time, that could add up because they are so tiny. On the other hand, if a baby overeats usually it comes back out. :-) I agree with other posters that we should look to our pediatricians for advice. I typically hear that if my child stays on the same growth curve over time, that’s good; deviations usually raise red flags to doctors.

  15. [...] news has fueled discussion over at Strollerderby, with one blogger writing, “Just to head off an argument I hear every time this issue is [...]

  16. Natalie says:

    I breastfed my first child until she was 2 years old. She was exclusively breastfed until she was 6 months old, then was given tiny amounts of solids and water until she was 8 months old, then started on solids 3 times per day. I continued to breastfeed her well after she started on solids and water. She was never given formula of any description. Her weight and height always hovered around the 50 percentile mark. In comparison, a friend had a baby prematurely, he was breastfed until 5 odd months, then put on to formula and solids. His weight just BALLOONED! He was HUGE! At 7 months, my daughter weighed 7.5 kgs, this little boy weighed 11 kgs. They were the same age. Crazy! Regular formula makes babies chubby … it has sucrose in it …. babies tend to overfeed on formula …. in general, they probably are not as settled as breastfed babies (that’s been my observation anyhow) so tend to be a bit more fussier and dummies and food make good “plugs” for little mouths. You only have to look at the correlation between the obesity epidemic that is raging in “western” countries and the increase in formula feeding ….. to realise that there are detrimental long term effects of formula feeding …. appetite, digestion, metabolism, natural instinct.

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