5.1 Body Changes

In early childhood, as in infancy, the body and brain develop according to influential epigenetic forces. Biology interacts with culture as children eat, grow, and play.

Growth Patterns

Size and Balance These cousins are only four years apart, but note the doubling in leg length and marked improvement in balance. The 2-year-old needs to plant both legs in the sand, while the 6-year-old cavorts on one foot.

KATRINA WITTKAMP/GETTY IMAGES

Comparing a toddling, unsteady 1-year-old with a cartwheeling 6-year-old makes some differences obvious. During early childhood, children slim down as the lower body lengthens, and fat decreases as children develop more muscle mass. The average body mass index (BMI, the ratio of weight to height) is lower at ages 5 and 6 years than at any other time of life. Gone are the toddler’s protruding belly, round face, short limbs, and large head.

The centre of gravity moves from the chest to the belly, enabling cartwheels, somersaults, and many other motor skills. The joys of dancing, gymnastics, and pumping a swing become possible. Toddlers often tumble, unbalanced—fortunately, they are close to the floor and thus don’t have too far to fall. Kindergartners race and rarely slip.

Increases in weight and height accompany this growth. Over each year of early childhood, well-nourished children gain about 2 kilograms and grow about 7 centimetres. By age 6, the average child in a developed nation

• weighs between 18 and 22 kilograms
• is at least 100 centimetres tall
• has adult-like body proportions (legs constitute about half the total height).

Improved Motor Skills

Motor Skills Children learn whatever motor skills their culture teaches, including cutting sausage with a knife and fork. Unlike this child in Germany, some never master this skill, because about one-third of adults worldwide eat directly with their hands.

NILS HENDRIK MUELLER/GETTY IMAGES

As the body gains strength, children develop motor skills, both gross motor skills (evident in activities such as skipping) and fine motor skills (evident in activities such as drawing). Mastery depends on maturation and practice; some 6-year-olds can ice skate or print legibly—but most cannot.

All, however, are physically active, practising whatever skills their culture and their friends value. If adults provide safe spaces, time, and playmates, skills develop. Children learn best from peers who do whatever the child is ready to try—from catching a ball to climbing a tree.

Nutritional Challenges

Nutrition at this age is very important for brain development. Because of this period of synaptic activity (which is discussed in greater detail later on), young children need high levels of fat in their diets. Up until 2 years of age, about 50 percent of their total calories should be dedicated to fat (e.g., whole milk). After about 2 years of age, the dietary fat should be reduced to no more than 30 percent of total calories, such as 1 or 2 percent cow’s milk (Zero to Three, 2013).

Over the centuries, families encouraged eating, protecting children against famine. Today, 2- to 6-year-olds in developed nations may be at greater nutritional risk than children of any other age because they may eat too much of the wrong foods. However, in the poorest nations, infant and early childhood malnutrition contributes to one-third of all child deaths (UNICEF, 2008) and slows later growth, including growth of the brain.

OverweightThe cultural practice of encouraging children to eat has turned from protective to destructive. One example is Brazil, where 30 years ago the most common nutritional problem was under-nutrition; now, it is over-nutrition (Monteiro et al., 2004), with low-income Brazilians being particularly vulnerable (Monteiro et al., 2007). In almost every nation, 4-year-olds are more often overweight than 2-year-olds. This suggests that habits, not genetics, are the problem.

Obesity in Canada, a joint report by the Public Health Agency of Canada (PHAC) and the Canadian Institute for Health Information (2011), noted that childhood obesity has been proven to increase the risk of obesity among adults, which in turn can lead to the early development of serious medical conditions such as Type 2 diabetes, heart disease, and high blood pressure. The report also estimated that the total economic costs of obesity in Canada range from $4.6 billion to $7.1 billion annually.

Victory! Well, maybe not quite yet, but he’s on his way. This boy participates in a British initiative to combat childhood obesity. Mother and son are exercising together in Liverpool Park in an effort to develop healthy lifestyles.

HOWARD BARLOW/ALAMY

Although obesity rates in Canada are lower than in the United States (between 2007 and 2009, 34 percent of Americans were obese compared with 24 percent of Canadians), a recent report from Statistics Canada and the U.S. Centers for Disease Control and Prevention indicated that Canada seems to be catching up, especially when it comes to rates of childhood obesity (Shields et al., 2011). Figure 5.1 shows that obesity rates in Canada increased significantly between 2000 and 2011. Also, according to the Government of Canada (2013a), over the last 25 years, Canada’s obesity rate has almost tripled among children and youth.

FIGURE 5.1 A Growing Problem A 2013 study at the University of British Columbia found that, on average, between one-quarter and one-third of Canadians are obese, depending on the region (Gotay et al., 2013). Rates of obesity are highest in the Atlantic provinces, Nunavut, and the Northwest Territories. These maps show a general, countrywide rise in obesity rates between 2000 and 2011. What could be some reasons for this upward trend?

What is most disconcerting is that childhood obesity seems to have dangerous effects on a person’s physical, emotional, and social well-being for years to come. Heart disease and diabetes are becoming epidemic as overweight children become overweight adults (Saul, 2008). A medical report predicted that by 2020, 228 million adults worldwide will have diabetes (more in India than in any other nation) because of unhealthy eating habits acquired in childhood. Children who are obese are more likely to suffer from low self-esteem, negative body image, and depression. They are also more likely to be teased and bullied by their peers (Government of Canada, 2013a).

Appetite decreases between 1 and 6 years of age; young children need fewer calories per kilogram. In addition, many children today get much less exercise than their grandparents did. They rarely help on the farm, walk to school, or play in playgrounds. Yet many adults still threaten and bribe their children to overeat (“Eat your dinner and you can have ice cream”). Most parents falsely think that relatively thin children are less healthy than relatively heavy ones (Laraway et al., 2010).

Nutritional DeficienciesAlthough most children consume more than enough calories, they do not always obtain adequate iron, zinc, and calcium. For example, children now drink less milk, which means weaker bones later on. Another problem is sugar. Many customs entice children to eat sweets—in birthday cake, holiday candy, desserts, and other treats. Carbohydrates such as breads also contain sugar, and so the total caloric intake of sugar becomes problematic.

Products advertised as containing 100 percent of daily vitamin requirements are sometimes misconstrued as a balanced, varied diet. In fact, healthy food is the best source of nutrition. Children who eat more vegetables and fewer fried foods usually gain bone mass but not fat, according to a study that controlled for gender and income (Wosje et al., 2010).

Eat Your Veggies On their own, children do not always eat wisely.

VAHAN SHIRVANIAN/CARTOONSTOCK

In developing nations, the lack of micronutrients is often severe due to a lack of variety of healthy foods. Studies have explored the effect of providing supplements, with mixed results. Providing micronutrients as part of fortified foods seems to have the best results (Ramakrishnan et al., 2011).

AllergiesUnfortunately, many parents face challenges in ensuring that their children are fed well nutritionally. Allergies are one such challenge. Between 3 to 8 percent of all young children have a food allergy, usually to a healthy, common food.

Diagnostic standards for food allergies vary (which explains the range of estimates). Treatment varies even more (Chafen et al., 2010). Some experts advocate avoiding the offending food. Many parents withhold their child’s first taste of peanut butter until after age 3 years. Others suggest building up tolerance, such as by giving babies a tiny bit of peanut butter (Reche et al., 2011). Many public schools and daycares are nut-free environments, where no child ever brings a peanut butter sandwich for lunch.

Same Situation, Far Apart: Eager Eaters Preschoolers generally eat whatever they get. These are the fortunate ones, enjoying cut-up fruit and vegetables (left), and sharing a fresh fruit snack with a friend (right).

COLIN MCCONNELL/TORONTO STAR VIA GETTY IMAGES
ZHANG BO/GETTY IMAGES

Since allergies are so common among young children, in 2012 the Government of Canada began to enforce stronger labelling regulations for food products containing allergens. The new regulations require food manufacturers to include clearer and more comprehensive labels on their packaging so that consumers can avoid products with ingredients that might make them ill. In drawing up the regulations, the government identified a list of 10 “priority allergens” that are most likely to cause serious reactions among Canadian consumers: peanuts, tree nuts, milk, eggs, seafood, soy, wheat, sesame seeds, mustard, and sulphites. The government also clarified its labelling requirements for gluten-free products to benefit the 1 percent of Canadians who have celiac disease (Health Canada, 2012a).

ObsessionsFeeding young children a varied diet is also complicated by the strong preferences that many of them have for routines. In some families, children are accustomed to having an after-school snack, regardless of whether they are actually hungry or not.

Similarly, some children insist on certain foods, prepared and served in a particular way. This rigidity, known as just right, is held strongly by many children because they have a desire for continuity and sameness. This occurs around age 3 (Evans & Leckman, 2006; Pietrefesa & Evans, 2007). Even familiar foods may be rejected if presented in a new way.

After age 5, rigidity fades (see Figure 5.2). The best reaction may be patience: A young child’s insistence on a particular routine, a favourite cup, or a preferred cereal can be accommodated for a year or two. For children, routines need to be simple, clear, and healthy; then they can be accommodated until the child is ready to change.

FIGURE 5.2 Young Children’s Insistence on Routine This chart shows the average scores of children (who are rated by their parents) on a survey indicating the child’s desire to have certain things—including food selection and preparation—done “just right.” Such strong preferences for rigid routines tend to fade after age 5.

Oral HealthToo much sugar and too little fibre cause another common problem, tooth decay, which affects one-third of all young Canadian children (Ontario Dental Association, 2008). Soft drinks and fruit drinks are prime causes; even diet soft drinks contain acid that makes decay likely (Holtzman, 2009). Health Canada notes that breast milk and fruit juice can also lead to tooth decay in young children since the sugars in these foods combine with the bacteria in tooth plaque to create an acid that damages tooth enamel (Health Canada, 2009). This is one reason why toothbrushing and trips to the dentist should begin even before age 3 (Mofidi et al., 2009).

Avoidable Injuries

Worldwide, injuries cause millions of premature deaths among adults as well as children. Not until age 40 does any specific disease overtake accidents as a cause of mortality (World Health Organization, 2010). Two- to 6-year-olds are at a greater risk for injury than slightly older children because of their limited physical coordination and cognitive abilities to judge whether activities are safe.

In Canada, unintentional injuries kill more children and youth (ages 1–14 years) than all diseases combined. Each year on average, almost 300 children die and 21 000 are hospitalized from unintentional injuries, which costs the health-care system about $4 billion annually in direct and indirect costs (Fuselli et al., 2011). The leading cause of fatal injuries in Canada for children aged 1 to 4 is motor vehicle accidents; drowning is the second leading cause of death (PHAC, 2009). In terms of non-fatal injuries, many lead to lifelong impairments such as blindness, restricted mobility, and developmental delays as a result of brain and spinal-cord injuries.

A VIEW FROM SCIENCE

Eliminating Lead

Lead was targeted as a poison a century ago (Hamilton, 1914). The symptoms of plumbism, as lead poisoning is called, were obvious—intellectual disability, hyperactivity, and even death if blood lead levels reached 70 micrograms per decilitre.

The lead industry defended the heavy metal as an additive, arguing that low levels were harmless and that parents needed to prevent their children from eating chips of lead paint (which taste sweet). Developmental scientists noted that the correlation between lead exposure and the symptoms mentioned above does not prove causation. Children with high levels of lead in their blood were often from low-SES families: Malnutrition, inadequate schools, family conditions, or a host of other reasons not related to lead could reduce their IQs (Scarr, 1985).

Toxic Shrinkage A composite of 157 brains shows reduced volume because of high lead levels. The red and yellow hotspots are all areas that are smaller than in a normal brain. No wonder lead-exposed children have multiple intellectual and behavioural problems.

CECIL KM, BRUBAKER CJ, ADLER CM, DIETRICH KN, ALTAYE M, ET AL. (2008) DECREASED BRAIN VOLUME IN ADULTS WITH CHILDHOOD LEAD EXPOSURE. PLOS MED 5(5): E112. DOI:10.1371/JOURNAL.PMED.0050112

Consequently, lead remained a major ingredient in paint (it speeds drying) and in gasoline (it raises octane) for most of the twentieth century. The fact that babies in lead-painted cribs, preschoolers living near traffic, and children in lead-painted homes were often mentally challenged and hyperactive was still claimed to be correlation, not causation.

Finally, chemical analysis of blood and teeth, better intelligence tests, and careful longitudinal and replicated research proved that lead was indeed a poison, even at relatively low levels (Needleman et al., 1990, Needleman & Gatsonis, 1990). In Canada, the federal government began reducing lead levels in paint in 1976, and today lead is no longer used in household paints. The Canadian government outlawed leaded gas for automobiles in 1990. Yet, some lead sources are still unregulated, resulting in high levels in drinking water and jet fuel. Some people feel that may be harmless. However, pediatricians have set the acceptable level, formerly 40 micrograms per decilitre of blood, at 10 micrograms or less. One team contends that even 5 micrograms per decilitre is too much (Cole & Winsler, 2010), especially in a young child whose brain is rapidly developing.

The result of policies and regulations to protect against the dangers of lead is that contemporary children in North America have much lower levels of lead in their blood. According to the Canadian Health Measures Survey, lead levels in the blood of Canadians aged 6–79 years have declined more than 70 percent since the 1970s (Statistics Canada, 2011c). Even so, 100 percent of Canadians still have some lead in their blood (Statistics Canada, 2013b). Children aged 3 to 5 years have slightly higher levels of lead than those aged 6 to 11 years.

In addition to governments implementing laws and policies to reduce exposure to lead, parents can take action as well. Specifics include increasing children’s consumption of calcium, wiping window ledges clean of dust, testing drinking water, replacing old windows, and making sure children do not swallow peeling chips of lead-based paint (still found in old buildings) (Dilworth-Bart & Moore, 2006; Nevin et al., 2008).

As well, every young child should be tested—only a pinprick of blood is needed. Repeated testing may be required if a child’s lead level is initially found to be high. Once the source (old paint, lead in the soil, glazed dishes, home medicines) is identified and eliminated, blood lead levels fall and the brain recovers.

Remember from Chapter 1 that scientists use data collected for other reasons to draw new conclusions. This is the case with lead. About 15 years after the sharp decline in the number of preschool children with high blood lead levels, the rate of violent crime committed by teenagers and young adults fell sharply. Year-by-year correlations are apparent.

A scientist comparing these two trends concluded that some teenagers commit impulsive, violent crimes because their brains were poisoned by lead when they were preschoolers. The correlation is found in every nation that has reliable data on lead and crime—Canada, the United States, Germany, Italy, Australia, New Zealand, France, and Finland (Nevin, 2007). Not everyone is convinced, but the research shows that, although correlation does not prove causation, it can suggest causes that no one imagined before.

The Canadian Paediatric Society (CPS) has pointed out that death rates from unintentional injuries among children and teens are three to four times higher in Aboriginal communities than elsewhere in Canada. Among Aboriginal children younger than 10 years of age, the leading causes of death due to injuries are fires and motorized vehicle accidents, including those involving snowmobiles and ATVs (Banerji, 2012). These disproportionately high rates have led the CPS to make six specific recommendations to reduce the number of deaths among Aboriginal children:

1. Focus on surveillance: Involve better data collection and research.
2. Improve education: Share information through conferences, public debates, and meetings with community members.
3. Strengthen advocacy: Cooperate among federal, provincial, and territorial governments in developing a national injury-prevention strategy.
4. Reduce barriers: Make particular efforts to reduce rates of poverty and substandard housing and increase access to drug and alcohol rehabilitation programs.
5. Evaluate initiatives: Measure the impact of injury-prevention programs.
6. Provide resources: Have effective funding for injury-prevention programs and research.

Could Your Child Do This? If acrobatics was your family’s profession and passion, you might encourage your toddler to practise headstands, and years later, your child could balance on your head. Everywhere, young children try to do whatever their parents do.

CHIEN-MIN CHUNG/GETTY IMAGES

Note that throughout this discussion, we have been referring to these injuries as “unintentional,” not “accidental.” Even though such injuries are not deliberate, public health experts do not call them “accidents.” The word implies that such an injury is random and unpredictable. Instead of accident prevention, health workers seek injury control (or harm reduction). Serious injury is unlikely if a child falls on a safety surface instead of on concrete, if a car seat protects the body in a crash, if a bicycle helmet cracks instead of a skull, or if pills are in a bottle with a child-resistant cap.

Environmental HazardsLess obvious than unintentional injuries are dangers from pollutants that harm young, growing brains and bodies more than older, developed ones. For example, in India, one city of 14 million (Kolkata, formerly Calcutta) has such extensive air pollution that childhood asthma rates are soaring and lung damage is prevalent. In these circumstances, supervision is not enough: Regulation makes a difference. In the Indian city of Mumbai (formerly Bombay), air pollution has been reduced and children’s health has been improved through several measures, including an extensive system of public buses that use clean fuels (Bhattacharjee, 2008).

A study in western Canada (Clark et al., 2010) examined the health impacts of air pollution. Some suspected pollutants, such as car and truck exhaust, were proven to be harmful to children, but others, such as woodsmoke, were not. Much more research on pollutants in food and water is needed.

Harm ReductionThree levels of harm reduction apply to every childhood health and safety issue:

• Primary prevention structures the environment to make harm less likely, reducing everyone’s risk of sickness, injury, or death. Universal immunization and less pollution are examples of primary prevention.

• Secondary prevention is more specific, averting harm in high-risk situations or for vulnerable individuals. For instance, for children who are genetically predisposed to obesity, secondary prevention might mean exclusive breastfeeding for 6 months, no soft drinks or sweets in the kitchen for anyone, and frequent play outside.

• Tertiary prevention begins after harm has occurred, limiting the potential damage. For example, if a child falls and breaks an arm, a speedy ambulance and a sturdy cast are tertiary prevention.

How would these three levels apply to preventing child deaths from drowning? Tertiary prevention might be immediate mouth-to-mouth resuscitation when a submerged child is pulled from the water; secondary prevention would have parents put life jackets on children before taking them onto motor boats; and primary prevention might be laws that swimming pools be enclosed by a locked fence on all four sides.

Tertiary prevention is most visible, but primary prevention is most effective (Cohen et al., 2010). Harm reduction begins long before any particular child or parent does something foolish. For developmentalists, a systems approach helps pinpoint effective prevention.

When a child is seriously injured, analysis can find causes in the microsystem, exosystem, and macrosystem. For example, if a child pedestrian is hit by a car, the analysis would note the nature of the child (young boys are hit more often than older girls) and the possible lack of parental supervision (microsystem); the local speed limit, sidewalks, and traffic lights (exosystem); and the regulations regarding drivers, cars, and roadways (macrosystem).

Researchers seek empirical data in any scientific approach. For example, the rate of childhood poisoning has decreased since pill manufacturers adopted bottles with safety caps—a useful fact when anyone complains about the inconvenience.

Some adults say that children today are overprotected, with fewer swings and jungle gyms, mandated car seats, and nut-free schools. Statistics—not anecdotes and memories (“I loved the metal monkey bars, and I am still alive”)—are needed, otherwise cultural assumptions may overtake effective injury control. Without evidence, people disagree as to when protection becomes overprotection, as the following explains.

Same Situation, Far Apart: Keeping Everyone Safe Preventing unintentional injury to children requires action by adults and children. In North America, adults passed laws and bought safety seats—and here a young boy buckles up his stuffed toy for safety (left). In France (right), teachers stop cars while children hold hands to cross the street—so no daydreaming or rebellious partners run off.

© BLUE JEAN IMAGES/ALAMY
DAVID R. FRAZIER/DANITADELIMONT.COM

OPPOSING PERSPECTIVES

Safety Versus Freedom

How far should schools go to accommodate children with allergies? My friend has a child with a peanut allergy, and she expects the school to go peanut free for him. On the one hand, it seems selfish to go to that extent for one child (or a few children). Wouldn’t a peanut-free area be enough? What about children with other food allergies? Should the school become egg-free as well? On the other hand, this kid can die if exposed to peanuts. Isn’t a little inconvenience worth saving his life? And is separating the child from everyone else discrimination? Will this cause bullying and other emotional problems? Is there a way to protect this child without disrupting everyone?

—Edited entry from an online parenting forum

Sara Shannon’s daughter Sabrina was a 13-year-old high school student with severe peanut, dairy, and soy allergies in Pembroke, Ontario. During the school year, Sara usually packed Sabrina’s lunch at home, but on September 29, 2003, Sabrina told her mom not to bother. She wanted to try the french fries in the school cafeteria. They weren’t fried in peanut oil, Sabrina said, so they should be okay.

Sabrina had the fries for lunch and almost immediately experienced an allergic reaction. Short of breath and disoriented, she walked to the school office, where she collapsed before staff could administer the anti-allergy drug epinephrine. By the time an ambulance arrived, Sabrina’s body was in what doctors call anaphylactic shock. Her heart stopped beating temporarily, and by the next day she was dead.

The coroner determined that Sabrina’s allergic reaction was probably the result of cross-contamination—the tongs used to serve the fries had also been used to serve poutine. Minute traces of the milk curds in the poutine were enough to send the young girl’s body into severe shock.

Sabrina’s untimely and tragic death made her parents resolve to do whatever they could to ensure that no other child would suffer a similar fate. Soon they were joined by families of other children with allergies, and together they formed organizations that lobbied provincial politicians.

As a direct result, in 2005 the Ontario government passed a law called An Act to Protect Anaphylactic Pupils: Sabrina’s Law. This was the first piece of legislation in the world designed to shield children with serious allergies from contamination threats at school. It has served as a model for laws and policy directives in several Canadian provinces. For example, Manitoba passed a similar law in 2008, and Alberta issued an Allergy and Anaphylaxsis Policy Advisory in 2007.

In the United States, several states now have laws or policy guidelines that clearly outline steps and procedures to make schools safer for children with severe allergies. In 2011, the U.S. federal government passed the Food Allergy and Anaphylaxsis Management Act (FAAMA), which identifies a set of “voluntary allergy management guidelines” for schools.(Smith, 2011).

Protecting Children Jamie Nackan-April from Toronto, Ontario, has multiple food allergies. She is one of the many children who benefit from Sabrina’s Law. Allergy groups are calling for clearer food labelling to help identify all ingredients to avoid potentially dangerous reactions.

TANNIS TOOHEY/TORONTO STAR VIA GETTY IMAGES

Although these initiatives have saved children’s lives, they have also created controversy. Some parents feel that the rights of the majority are being compromised for the sake of a minority. Although the number of children with food allergies has definitely risen over the last several years, they still make up less than 5 percent of the total under-18 population (Branum & Lukacs, 2008).

Most of the controversy centres on so-called “nut-free schools,” where administrators have banned peanuts and other allergens from school cafeterias and from packed lunches that students bring from home. For example, in March 2011, parents in Edgewater, Florida protested outside the local public school after administrators not only declared the school a nut-free zone, but also directed students to wash their hands and rinse their mouths twice a day before entering the classroom, and brought a peanut-sniffing dog into the school over the spring break (Liston, 2011).

What do developmentalists think of this? Dr. Nicholas Christatis, a Harvard professor and social scientist, was quoted in Time magazine in 2009 criticizing some of the more extreme precautions schools have taken as a form of “societal hysteria.” “There are some kids with severe allergies,” said Dr. Christatis, “and they need to be taken seriously, but the problem with a disproportionate response is that it feeds the hysteria” (Sharples, 2009).

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Dr. Robert Wood of the Johns Hopkins Children’s Center also cautioned against allowing a few controversial examples to detract from the sensible approach most schools are taking in protecting allergic students: “There are definitely situations where we see a fear of the allergy that develops far out of proportion to the true risk, but for the vast majority of schools, things are mostly on balance and in perspective” (Sharples, 2009).

It’s important to note that none of the measures such as Sabrina’s Law in Canada or FAAMA in the United States specifically mandates nut-free zones or schools. Sabrina’s Law has two major provisions:

• Every school board must establish and maintain an anaphylaxis policy.
• School principals must develop individual safety plans for allergic students.

It is up to the individual boards and principals to decide exactly how to implement these directives.

An issue such as this, which pits individual safety against the right of people to eat what they please, will probably never be resolved to everyone’s satisfaction. Opinions are influenced not only by whether one’s child has food allergies, but also by cohort, culture, and personality. Perhaps the best way to close this particular discussion is with a comment from Sabrina Shannon’s mother, Sara.

“We have to make sure this doesn’t happen again,” Sara told an interviewer in regard to Sabrina’s death. “When everything is done, everything is in place, every procedure, every emergency plan, then if a child dies, we can say, ‘There was nothing we could do.’ But when we know there is something we can do to prevent this, we can’t live in a world of denial” (Smith, 2011).