Which of the following is used to assess growth patterns of infants and children?

When James and Rebecca Ortega brought their newborn daughter, Avery, to the pediatrician for her first visit last December, the doctor plotted her height, weight and head circumference on a growth chart, a standardized graph that gives parents a picture of how well their child is growing.

The Ortegas, who live in Alexandria, were surprised to learn of their daughter’s seemingly disproportionate size: Her height was in the 75th percentile, her weight in the 50th, and her head relatively huge — in the 98th percentile.

“I immediately thought that she had elephantiasis,’’ a disease characterized by swollen body parts, Rebecca Ortega says. The pediatrician reassured the Ortegas that Avery’s head size and development generally were normal. Indeed, with age, Avery’s head has become more proportional to her body.

Still, Ortega wonders whether pediatric growth charts are less helpful than they are anxiety-producing — encouraging worry, guilt, even competitiveness in parents who may not understand them.

“They drive people to compare their babies to others when, in fact, all babies grow and develop at different rates. In our comparison-prone world, we certainly don’t need more fuel for the fire,” Ortega says.

Typically, pediatricians weigh and measure children approximately every few months until age 2 to 3 and then yearly after that. They look for steady and proportional growth in height, weight and head circumference, an indicator of brain development. As long as a child continues to gain weight and height proportionally over the years — even if he or she remains in a lower-than-average percentile — it is an indication of steady growth.

Deviations from a steady growth curve can indicate such problems as nutritional inadequacies, growth hormone deficiencies, metabolic disorders and obesity. Sometimes, a faltering growth pattern can be a sign of a more serious disease, such as cystic fibrosis.

Doctors and other health professionals in the United States began using growth charts in 1977. Over time, pediatricians began routinely sharing them with parents, a practice that probably grew from growing consumer activism, when many patients began insisting on getting more medical information and having a greater role in medical decision-making for themselves, and, in this case, their children.

“Parents like to see them,” says Francis M. Palumbo, a pediatrician and associate professor of pediatrics at Georgetown University School of Medicine. But the terminology can be confusing.

“Growth numbers are described in percentiles, and everyone thinks they should be close to 100 because that’s how we were graded in school,’’ says Van Hubbard, director of the National Institutes of Health’s Division of Nutrition Research Coordination. “But in growth, higher is not necessarily better. The most important thing is to look at growth patterns, wherever they fall on the chart.’’

A 2009 study of 1,000 American parents found that most of those who thought they understood growth charts actually had trouble interpreting them. The study, which appeared online in the journal Pediatrics, found that 79 percent of the parents surveyed said they were familiar with growth charts, yet when provided with questions and multiple-choice answers, only 64 percent could identify a child’s weight when shown a plotted point on a growth chart. Only 68 percent could identify the percentile of the plotted point, and only 56 percent could identify the definition of percentile. Up to 77 percent incorrectly interpreted charts containing height/weight measurements in tandem.

‘A terrific tool’

The pediatric growth chart is “a terrific tool for health-care practitioners to track children’s growth, which it was initially developed for, but the question is whether it should be used as an educational tool for parents, because it wasn’t designed for that,’’ says pediatrician Elana Pearl Ben-Joseph, one of the authors of the 2009 study. “I think you can create some kind of visual display of information that is easier for a parent to understand than an X axis and a Y axis and percentiles.’’

The growth charts are a series of curves that illustrate the distribution of body measurements by sex and age. If a 3-month-old girl, for example, is in the 40th percentile for weight and the 80th for height, it means that, compared to 100 representative girls the same age, she is heavier than 40 of them and taller than 80 of them. This seems fairly straightforward, but “many parents don’t grasp the concept of percentiles, no matter how it is explained to them,’’ Pearl Ben-Joseph says.

The earliest infant growth charts in the United States were based on a sample of white, bottle-fed babies born in Yellow Springs, Ohio, between the 1920s and mid-1970s. In 2000, the Centers for Disease Control and Prevention developed a new set of charts with data from a cross-section of U.S. children, including a more diverse population and children who were both breast-fed and formula-fed.

In 2006, the World Health Organization released international growth charts for children up to age 5, reflecting what WHO officials consider the optimal standards for children’s growth, such as breast-feeding, healthy nonsmoking parents and high socioeconomic status. The curves were based on data from selected communities worldwide.

The WHO charts describe how healthy, breast-fed children should grow under the best possible environmental and health conditions; the CDC charts describe how children actually grew in a particular place and time — the United States, between 1963 and 1994 — and take into account other factors, such as formula feeding.

The WHO and CDC charts show different patterns that might cause pediatricians to come to conflicting conclusions about growth, since breast-fed babies typically gain weight faster at first than formula-fed infants.

In 2010, CDC recommended that U.S. pediatricians use the WHO charts from birth to age 2 and the CDC charts for older children. The agency made the recommendation to encourage breast-feeding during the first two years of life; also, the agency hopes that using the WHO standards will prompt pediatricians to consider environmental factors in evaluating any departure from a normal growth pattern. It’s unclear how many pediatricians have begun to follow this recommendation.

To be sure, not all children are breast-fed, nor do they all grow up in the most healthful environments, “so you need to understand what your kid is being compared to,’’ says Cynthia Ogden, an epidemiologist with the CDC’s National Center for Health Statistics, who served on the committee that revised the CDC charts. “That understanding is important before you interpret the numbers and discuss with your clinician what the implications are.’’

‘Just one piece of information’

Of course, children come in a variety of shapes and sizes, and their growth rates vary widely. “Growth charts represent the whole distribution of children, and they are just one piece of information,’’ Ogden says.

Atlanta pediatrician Jennifer Shu, co-author of “Food Fights,’’ a nutrition guide for parents, agrees. “Although the charts are commonly used to graphically illustrate the typical growth patterns for boys and girls, it is important to note that they do not accurately reflect the growth of all children,’’ she says. Also, “there is a large range of normal. . . . If the child is small and the parents are also small, I look for general trends: Is the child’s growth following the shape of the standard growth curves, and does it appear the child will reach the parents’ size in adulthood if you continue tracking along that same line?’’

“Growth charts can give objective information when eyeballing a child isn’t accurate enough,’’ Shu adds, citing a case of a patient of hers “who was falling off the growth chart at around 9 months of age. His mother was concerned, but the original pediatrician kept saying he was fine. He ended up getting a G-tube [gastric feeding tube] for a few years for his feedings.”

Similarly, Washington pediatrician Palumbo has diagnosed several health problems first seen through the growth charts. One of his patients, a child adopted from India, “was always on the small side, and of course we had no biological family history,’’ he says.

Adoption, particularly international adoption, can present additional challenges when evaluating growth, since, as Palumbo points out, there typically is no biological family history available. Moreover, most international adoptees were bottle-fed and often received inadequate care in their native countries before joining their new families. If an internationally adopted child plots in an unusually low percentile, or shows flat or declining growth, pediatricians often will test further, if only to rule out additional problems.

After showing the family the charts and discussing possible diagnoses, the boy was tested and found to have a growth-hormone deficiency. He began therapy two years ago at age 8 and “has had a good response,’’ Palumbo says.

Still, Palumbo admits, sometimes it’s not always effective to share growth charts with parents. “Some like to see them, and I show them, but it’s often easier just to say, ‘Your child is doing fine,’ ” Palumbo says. “They’re valuable when you have parents who come in and say, ‘Oh my God, he doesn’t eat.’ Then it’s helpful to be able to show them a nice normal growth curve.’”

Perhaps tracking a child’s growth is just a matter of common sense, suggests Shu. “Do they eat well, and are they happy and developing?’’ she says. “The bottom line: Look at the child and not just the numbers.’’

Cimons, a former reporter for the Los Angeles Times, lives and writes in Bethesda.