A new systematic review showed early identification of at-risk infants along with early and sustained intervention are key when targeting the most vulnerable infants.
The importance of starting early to prevent childhood obesity is well established, as there are more children starting school with existing overweight and obesity. Pregnancy and infancy present ideal opportunities for action: parents often look for health advice during pregnancy, and they may be particularly motivated to adopt healthier behaviours early on to protect infants against later obesity. Recent years have seen a proliferation of child obesity interventions during the first 1000 days of life, which are aimed at preventing unhealthy weight gain in infancy and beyond.
However, many interventions take a broad-ranging approach to preventing excess weight gain, focusing universally on all pregnant women in a population or all infants up to the age of two. This new systematic review looks more specifically at interventions targeting children and families most in need of support, as a means of increasing impact and channelling scarce health resources effectively.
The authors reviewed over 27,000 titles from six databases, searching for studies that a) were delivered before age two, b) specifically aimed at infants at high risk of childhood obesity and c) reported weight outcomes beyond 28 days. Forty-nine papers from 38 studies met these criteria, addressing 10 antenatal interventions, 16 postnatal and 12 conducted both before and after birth. The most common risk factors for childhood obesity investigated were low family income (sometimes in conjunction with criteria such as adolescent mothers) and high maternal pre-pregnancy BMI or gestational weight gain. None of the selected studies targeted paternal weight status. Other risk factors for childhood obesity were gestational diabetes, formula feeding, specific ethnic groups and infants with disturbed sleep. Most interventions focused on infant and/or maternal nutrition, although others addressed physical activity and two examined alternative medications for gestational diabetes.
The studies varied widely in design, scale and quality – for example, several studies did not report how closely participants kept to the intervention plan and how many participants dropped out of the study. The 38 studies reported outcomes at different timepoints in early childhood and they used different measures, making it impossible to conduct a meta-analysis.
In all, nine interventions of varying quality reported evidence of significantly improved child weight trajectory on at least some measures, although effects tended to diminish over time. Two studies of limited quality reported significantly worse weight outcomes in the intervention group compared to controls. One common factor among the studies with positive weight outcomes was their sustained duration; most continued to 18 months or beyond, typically offering regular support to parents. All but one of the successful interventions were delivered by health professionals. Most of the antenatal interventions commenced early in pregnancy. All the postnatal studies identified started at birth or within the first few months of life. This highlights the importance of monitoring early infant growth and communicating with parents as soon as rapid weight gain is identified to initiate behaviour change and support.
While previous systematic reviews of early intervention studies have explored the impact among general populations of infants, this is the first review to focus specifically on children who are most susceptible to unhealthy weight gain. Overall, it provides limited evidence that a focus on the most at-risk in early life can be beneficial: around one quarter of the identified studies showed significantly improved weight outcomes among intervention cohorts.
The review demonstrated the importance of not only working with parents of infants under two years, including expectant parents, but also pinpointing infants who face greater risks of excess weight gain. Parental and socio-demographic risk factors for later obesity are well established and most can be identified early. It is vital that these infants receive evidence-based programs early to prevent unhealthy weight gain. The review highlighted the importance of sustained duration including contact with health professionals.
Chris Rossiter, Heilok Cheng, Jessica Appleton, Karen J. Campbell & Elizabeth Denney-Wilson (2021) Addressing obesity in the first 1000 days in high-risk infants: a systematic review. Maternal & Child Nutrition. DOI: 10.1111/mcn.13178