Early Childhood Development: Probing Early Life Risk Factor Surveillance

For Children Under the Age of Five, We Do Far too Little!

“It’s estimated that by the end of childhood, 40 percent of Canada’s children are dealing with complications of overweight or obesity, asthma, injury, behaviour problems or learning difficulties,” says Dr. Jonathon Maguire, a pediatrician and researcher at the Li Ka Shing Knowledge Institute of Toronto’s St. Michael’s Hospital. But Maguire’s warning extends far beyond children’s health. Because health in childhood presages health in adulthood, he emphasizes, the implications of Canada’s child health crisis will resound for decades to come. “Unknowingly,” Maguire laments, “we are marching our children down a thorny path to a battle with adult chronic disease.”

Maguire’s worries are well-grounded in data from numerous large, long-running surveillance efforts monitoring the health of Canadian children. These include the Canadian Community Health Survey and the Canadian Health Measures Survey, which are both coordinated by Statistics Canada, as well as The Public Health Agency of Canada’s Health Behaviour in School-Aged Children Study and the Canadian Pediatric Surveillance Program, which involves a network of 2,500 pediatricians probing rare conditions. It’s a respectably comprehensive mix, Maguire acknowledges. But it suffers from a gaping deficiency, he warns. “Although we do a good job gathering information about kids over the age of five, when it comes to surveillance of children under the age of five, we do far too little.  And we know now that much of what happens through one’s life is set up in the first five years.”

To help overcome the dearth of detailed health data for children under five, Maguire and a small number of other ambitiously innovative Canadian researchers have launched probes into early-life risk factors for a broad suite of diseases ranging from diabetes to depression. It’s not an easy task. Doing it requires close collaboration with very young children and their families in the face of logistical, emotional and legal barriers that deter surveillance of very young children. These barriers can prove defeating: Just months ago, the US National Institutes of Health cancelled an ambitious, multi-decade study of environmental influences on children's health after spending US$1.2 billion on the effort and enrolling roughly 5,700 children in a pilot study at 40 centres. One of the key problems that defeated the study was the difficulty of recruiting children and families.

In Toronto, Maguire helps lead two major studies probing early-life risk factors. The first of these is TARGet Kids!, a Canadian Institute for Health Research-funded effort involving 7,000 newborn children enrolled with 50 physicians. So far, says Maguire, the study has generated 25 published articles. Some of the most interesting work has focused on nutrition. Maguire’s co-investigator Dr. Patricia Parkin, who is research director with the pediatric outcomes research team at The Hospital for Sick Children in Toronto, has found that more than 15 percent of children under five suffer from iron deficiencies likely stemming from over-consumption of cows’ milk – with between one and two percent suffering iron deficiency anemia significant enough to impact brain development. “The gap in data on this topic was pretty substantial,” says Parkin. “There are simply no national data on iron deficiency in children. The TARGetKids! study is amassing good data on this now.”

Catherine Birken, another researcher at The Hospital for Sick Children, serves alongside Maguire and Parkin as a co-leader for the TARGetKids! study. Her focus is on childhood obesity. Once again, she says Canada lacks national data for very young children on this issue. “We’re doing a terrible job collecting national numbers,” Birken complains. Through TARGetKids!, Birken aims to address this deficiency. “We’re gathering longitudinal growth data on the kids enrolled in the study, and very deep information on child health behaviours including screen time and sleep patterns.” 

The key to the TARGetKids! study, Parkin, Maguire and Birken all agree, is the integration of family physicians into the project. This allows the TARGetKids! team to use “fly on the wall” techniques to gather data collected from children during routine appointments and checkups – an approach Maguire refers to as “practice-embedded” and one that takes advantage of the fact that “kids go to the doctor all the time.” Although the study largely relies on routine data, it also gathers data from non-routine sources such as blood samples, Parkin notes. “We’re not aware of any other studies of this sort which are embedded in primary care settings,” she adds.

But TARGetKids! aspires to do more than simply track data gathered during children’s encounters with doctors. Within the framework of a second study known as the Ontario Family Health Study, clinical data from the TARGetKids! cohort is being meshed with administrative data from the Ontario Health Insurance Plan as well as with data from two large studies of Ontario newborns. The hope, says Maguire, who co-leads the Ontario Family Health Study, is to expand the cohort to a total of 20,000 children in order to “reconstruct early childhood and probe the roots of disease” utilizing data from what he describes as one of the “largest, most comprehensive and technologically sophisticated pregnancy and early childhood cohorts in the world.” 

The long-term goal, explains Laura Anderson, a research fellow with both TARGetKids! and the Ontario Family Health Study, is to follow the children though infancy and childhood in order to investigate “the gene-environment interactions that establish developmental trajectories to health, learning and social functioning.” By using advanced technologies to “predict sub-optimal human potential and expose early causal pathways and relationships in the first 4 years of life,” says Anderson, she and the other researchers involved hope “to develop interventions that can be applied to children early in life to take advantage of the plasticity of a child’s developmental systems.”

Although the Toronto-based Ontario Family Health Study and TARGetKids! are the most ambitious efforts to track early childhood risk factors yet attempted in Canada, several other important studies are underway elsewhere in the country. The longest-running of these is the Quebec Longitudinal Study of Child Development, which began tracking a cohort of more than 2,000 children from their births in 1998. Focusing on themes in social, mental and physical health, this study has generated hundreds of journal articles, MA and PhD theses and research reports. 

Data from the first phase of the study (1998-2002) enabled researchers to evaluate the influence of family, child care and the broader social environment, alongside studies of motor, social and cognitive development, behaviour, diet, and sleep. Data from the second phase of the study (2003-2010) yielded reports on vocabulary acquisition, school readiness and adjustment to the school environment, physical activity and health, help with homework, summer child care, excess weight in children, diverse and changing family structure, child care, sleep, motivation, peer victimization, and predicting academic achievement. A third phase of the study launched in 2011 aims to examine themes in adolescence including work-school-play balance, romantic relationships, risky behaviour (smoking, alcohol and drug use, gambling), school motivation and educational aspirations, bullying, school violence and dropping out. 

Three other studies currently underway also promise to widen understanding of early-life risk factors for chronic diseases. In Alberta, the Alberta Pregnancy Outcomes and Nutrition (APrON) study has been tracking the role of nutrition in mental and neurodevelopmental disorders and long-term neurocognitive function in a cohort of 2,300 women since 2013. The focus areas so far have largely been postpartum depression and the impacts of breastfeeding. 

In Hamilton, Ontario, the Canadian Healthy Infant Longitudinal Development Study (CHILD) is probing the root causes of allergies and asthma, including genetic and environmental triggers and the ways in which they interact from pregnancy through childhood, in 3,629 families. The aim is to probe a suite of risk factors, including some which are already well-recognized such as traffic-related air pollution, dust mites, and cockroaches, as well as newer hypotheses, including semi-volatile organic compounds such as phthalates.

On a similar theme, at Health Canada in Ottawa, the Maternal-Infant Research on Environmental Chemicals (MIREC) study has recruited close to 2,000 women from cities across Canada during the first trimester of pregnancy. The study measures the extent to which pregnant women and their babies are exposed to environmental chemicals, as well as tobacco smoke, to assess what health risks, if any, are associated with exposure to elevated levels of environmental chemicals. Although smaller in number of participants than several international studies, this study has one of the most extensive datasets on prenatal exposure to multiple environmental chemicals in the world. <>