Ten studies (n=at least 1,913 participants, range nine to 1,062) reported in 12 articles were included in the review. There were three randomised controlled designs (all fair quality), two quasi-experimental designs (poor quality), two before-and-after studies (poor quality) and three cohort studies (poor quality). Three of the randomised studies were contained within one larger trial. Limiting features were small sample sizes, lack of appropriate control, high loss to follow-up (mean 32%, range 7% to 74%), confounding, poorly described interventions and invalidated or poorly-defined outcome measures.
Modest improvements were reported for parental reports of dietary intake, knowledge of health nutritional behaviours and attitudes (six studies). One large trial (n=1,065) included in this result showed that dietary fat intake was significantly reduced by 3g to 5g per day, fat as a percentage of dietary intake was reduced by 1.7% to 3.0% (maintained over 10 years of follow-up), cholesterol consumption was reduced by 20 to 29 mg/dL and (in boys) total serum cholesterol and non high-density lipoprotein cholesterol were significantly lower in the intervention groups (reductions of 11mg/dL to 15mg/dL for total serum cholesterol and 9mg/dL to 14mg/dL for non high-density lipoprotein cholesterol). There were no statistically significant differences between groups for overall energy intake and mean child weight.
None of the other studies showed any material differences in maternal body mass index, child weight-for-age percentile or proportions of overweight children. It was difficult to draw conclusions from some studies due to methodological limitations.
Eight on-going trials were identified, but could not be included in this review as results were not yet available.