The follow-up study of more than 800 New Zealand mothers who were provided a range of interventions aimed at preventing their infants growing up to be overweight or obese has just been published in the The American Journal of Clinical Nutrition.
Professor Barry Taylor, Dean of the Dunedin School of Medicine and study co-lead, describes the results as “amazing” and the long-term benefits, despite no ongoing contact, as “almost unheard of” for obesity interventions.
Professor Rachael Taylor, Director of the Edgar Diabetes and Obesity Research Centre and co-leader of the Health Research Council-funded research project said one in three New Zealand children is overweight or obese by the time they start school and treating obesity once established is ‘challenging’.
The team’s initial Prevention of Overweight in Infancy (POI) study showed that a brief sleep intervention in infancy reduced the risk of obesity at age two years while the nutrition and activity interventions (see details below) had no apparent impact.
In the follow-up study the researchers’ contacted the families again when the children were three-and-a-half and five-years-old to see what ongoing influence the interventions had had and found that the sleep interventions continued to have a positive impact in reducing the risk of obesity.
“Sleep is a very important behaviour that we need to consider,” said Rachael Taylor. “In terms of maintaining a healthy weight, sleep usually isn’t the first behaviour that comes to mind – for parents or health practitioners – yet the research is actually very clear.”
“The relationship between not getting enough sleep and being at higher risk of obesity is actually stronger than the evidence base for nutrition or activity, where the findings are often more mixed.”
In fact the children receiving just the conventional (FAB) nutrition and activity intervention were unexpectedly found to have ‘significantly higher’ body mass index (BMI) scores than the children in the control group at age five – but not when they were aged three-and-a half.
“Whereas the positive outcomes from a less conventional sleep intervention remained promising at age 5 years. More intensive or extended sleep intervention might have larger or longer-lasting effects and should be investigated,” the research team concluded and further research is planned.
For the sleep intervention, the pregnant women and their partners were invited to a group discussion based on what to expect, sleep-wise, with their baby in the first few months and how to prevent sleep problems.
When the babies were about three weeks old they were visited at home to see how sleep was going. The researchers talked to parents about assisting their child with sleep by learning to recognise signals from the baby that they were tired, and then encouraging baby to settle themselves to sleep. If a sleep problem developed, expert support was immediately available until infants were two years old. About a quarter of parents took up this support.
For the ‘FAB’ nutrition and activity intervention, mothers had access to a lactation consultant at least two times during the first few months of feeding, researchers visited them to discuss how to eat healthily as a family, and Sport Otago ran group sessions for parents and babies about being physically active as a family.
Barry Taylor, who also runs a special clinic for very overweight children, said it was important for children to have a regular sleep routine. He said children should go to bed at a time that gives them enough sleep so that they are not tired the next day, and screen-time should be avoided for at least 30 minutes before going to bed, as well as in bed.
Health Research Council Chief Executive Professor Kathryn McPherson said the study findings were of real interest and had a very practical application.
“It can seem, and be, difficult for children to go to sleep without external aids but, this programme shows that even very young infants can learn to do so relatively quickly – and that combined with a few other strategies, it works not just for better sleep but for better health.”
All four groups in the randomised controlled trial (the three intervention groups and the control group) received standard Well Child/Tamariki Ora care with additional support for the three intervention groups in:
- FAB (promotion of breastfeeding, healthy eating, physical activity: 8 contacts, antenatal, 18 months)
- Sleep (prevention of sleep problems: antenatal, 3 weeks and access to expert support if sleep problems developed)
- Combination (both interventions).
- Children in the FAB group had significantly higher BMI z scores than did Controls at age 5 years (adjusted difference: 0.25; 95% CI: 0.04, 0.47) but not at age 3.5 years
- Children who received the Sleep intervention (Sleep and Combination groups) had significantly lower BMI z scores at age 3.5 y (−0.24; 95% CI: −0.38, −0.10) and at age 5 years (−0.23; 95% CI: −0.38, −0.07) than children who did not (Control and FAB groups).