Canada adopts “leaner” growth charts

These are the World Health Organization’s charts showing normal, healthy weights for children at each age. There are separate charts for boys and girls. The horizontal axis is age and the vertical axis is weight.

Canadian health organizations are ready to adopt standard growth charts for babies and children that are based on World Health Organization standards. The charts use the growth pattern of a healthy, breast-fed baby. The charts being discarded are the U.S. charts created by the Centers for Disease Control, which are patterned on a bottle-fed baby. Breast-fed babies grow more slowly and with less fat. The new charts will put children at the top of the U.S. “healthy” range into the “obese” category. And fewer children will be marked as failing to thrive.

While they [the charts] are a standard tool for detecting potentially serious dips in a child’s development, they don’t always capture the whole picture. This is especially true of breast-fed infants, who can be leaner than formula-fed babies, especially in the six- to nine-month age range.

Now, a number of Canadian public health organizations representing doctors, nurses and dietitians are poised to adopt the 2006 World Health Organization international growth charts in place of the U.S.-based growth charts that were created by the Centers for Disease Control and Prevention.

In addition to recognizing the growth patterns of breast-fed babies, the WHO charts are also likely to reclassify those whom the CDC charts may have termed normal as overweight or obese.

“The WHO is the newest kid on the block in evaluating growth,” says Calgary pediatrician Ted Prince, adding that with the U.S. charts, weight has been steadily climbing, and the WHO standards “have been more constant.”

The Canadian Paediatric Society’s nutrition and gastroenterology committee, led by Valérie Marchand, a pediatric gastroenterologist at St. Justine’s Hospital in Montreal, is one of the groups looking at updating measurement policy. Dr. Marchand expects the committee to release the new policy by the end of the year.

The CDC charts are based on data gathered in five nationally representative surveys conducted between 1963 and 1994 in the United States. The 2000 charts are based on a representative sample of breast-fed and formula-fed children.

The recent WHO charts are based on a sample of 8,500 children between 1997 and 2003 in Brazil, Ghana, India, Norway, Oman and the United States.

Only breast-fed children in healthy environments – non-smoking households, for instance – are included in the sample. Measurements were taken 21 times between birth and the age of 5.

“The WHO charts are excellent because they are based on how a child in the best condition should grow,” Dr. Marchand says. She and her colleagues will recommend the adoption of the organization’s weight, height, BMI (body mass index) and head circumference measurements, based on age.

By conducting an international study, the WHO found there is actually little difference between children from different races or continents, Dr. Prince says. “Even across different socioeconomic populations, the growth is pretty constant.”

It may also be a relief for parents of breast-fed children. The growth of those babies often slows for a few months at around the age of six months.The CDC charts can create doubt in a mother’s mind, Dr. Marchand says.

“You’ll think, well, my child is not growing properly,” she says. “Maybe I don’t have enough milk, maybe I’m doing something wrong. Using growth charts that are for breast-fed babies will help those mothers feel more secure about their breastfeeding.

“Now that we are promoting breastfeeding, we really want to have a growth chart to reflect that to avoid misconceptions about growth and breast-fed infants.”

Over all, the weight-for-height and BMI figures are a little lower on the WHO charts compared with the CDC’s. As excess weight and obesity have grown in the United States, the heavier weights have been normalized.