Using data collected from more than 8,000 people over 42 years, researchers identified a high risk of increased body mass index (BMI) in one particular group of people who reported a larger than average exposure to formal (nurseries and preschools) and informal (playgroups) childcare.
They found that the participants who started childcare before they were three-years-old and who attended three-to-five days-a-week had a 0.509kg/m2 higher BMI aged 10 and 1.356kg/m2 higher BMI at 42, compared to those who first started childcare aged four and up and who only attended one or two days-a-week.
BMI is calculated using height and weight with a healthy score ranging between 18.5kg/m2 and 25kg/m2.
She said: “While this finding is important in and of itself, the real gap in the literature is that, after childhood, we know almost nothing about how exposure to childcare might be related to BMI trajectories in the long-term.
“The key finding of this research is that greater exposure to childcare, regardless of it being formal or informal, resulted in higher estimated BMI up until mid-adulthood, perhaps with intensity being more harmful than age at start of childcare attendance.
“Additionally, research has shown that a one-unit increase in young adulthood (18-30 years of age) BMI is related to an 8% increased risk of coronary heart disease.
“As such, the predicted differences in BMI seen the children who started childcare before three years of age and attended three-to-five days-a-week are of clinical significance.”
She also said the results are important for understanding how to use childcare as a positive platform for teaching youngsters about healthy behaviour.
“These results show that starting childcare at an earlier age and attending more frequently can affect BMI in later life and have an influence that persists from late-childhood to mid-adulthood.
“In today’s society, where most adults are working at least in part-time employment and parental leave tends to last for only one year or less, the use of childcare is both necessary and highly prevalent.
“As such, strategic research is urgently needed to understand what policies and practices regarding physical activity, sedentary behaviour, and diet exist and are implemented in these settings, and how these could be changed so that childcare plays a key role in the establishment of healthy behaviours and weight across the life course, instead of being associated with a more adverse BMI trajectory.”
The researchers used the 1970 British Cohort Study (BCS1970), which gave them access to data related to more than 17,000 people born during the same week in April, 50 years ago.
It asked about childcare attendance (no, yes), type (formal – preschool, creche, nursery; informal - playgroup), age at start, and intensity of attendance.
Data collection regarding BMI then took place at ages 10 (1980), 16 (1986), 26 (1996), 30 (2000), 34 (2004), and 42 (2012) years.
Dr Costa said: “The big plus of using BCS1970 is that it is a population representative sample with a large sample size, which allowed us to look at BMI from childhood to mid-adulthood.
“This, of course, is not possible in newer cohorts simply due to the timespan needed, so it gives us an indication of what might be happening in the very long run.
“Nevertheless, as childcare policies and practices have evolved since the 1970s, we now need further research using information from these newer cohorts to see if there is evidence of the same or different effects, after for example the introduction of national requirements for childminders and other childcare providers with the Children Act 1989.”
The paper, Associations of childcare type, age at start, and intensity with body mass index trajectories from 10 to 42 years of age in the 1970 British Cohort Study, has been published online in the journal, Pediatric Obesity.