Randomised controlled trials (RCTs) and non-randomised controlled trials of women enrolled before the third trimester of pregnancy were eligible for inclusion. Eligible trials had to compare behavioural and educational interventions with standard maternity care and assess any of the outcomes of total gestational weight gain, rate of gestational weight gain, and/or the proportion of women exceeding the Institute of Medicine weight gain recommendations. Trials were excluded if they evaluated weight-reducing pharmaceutical or surgical interventions, or if they only included women with any type of diabetes mellitus.
The included trials evaluated a variety of interventions that included one or more of dietary counselling, nutritional education, behavioural interventions, educational mail shots, use of individual weight-gain grid, physical activity, and/or education of women or care providers. Interventions varied in intensity, frequency and duration. Trials included women in the ollowing weight categories: any weight; normal or overweight; obese. Most trials included women aged over 18 years. Some trials focused on specific populations (African-American teenagers, low-income populations, and Cree Indians). Trials were conducted in the USA, Canada and Scandinavian countries.
The authors did not state how papers were selected for the review.