Background/Objectives: Obesity-related adverse health consequences are closely associated with abdominal obesity. Risk factors for overweight and obesity have been studied but there is a lack of information regarding risk factors for abdominal obesity, especially in the preschool population. The aim of the present study was to examine early life risk factors for an increased waist-to-height ratio (WHtR) in children at five years of age and, in addition, to investigate if these risk factors also were associated with overweight or obesity. 

Subjects/Methods: The study population comprised 1,540 children from a population-based longitudinal birth cohort study that included 2,666 Swedish children. The children were included if they had complete growth data for the analyses used in this study. Children were classified as having WHtR standard deviation scores (SDS) ≥ 1 or < 1 at five years of age, according to Swedish reference values, and as having body mass index standard deviation scores (BMI_SDS) for overweight/obesity, or normal weight/underweight according to the International Obesity Task Force criteria. Associations between child-related, socioeconomic status-related, parental health-related and nutrition- and feeding practice-related factors during the first two years and a WHtR_SDS ≥ 1 or a BMI_SDS for overweight/obesity at five years were investigated with logistic regression analyses. 

Results: At five years of age, 15% of the children had WHtR_SDS ≥ 1 and 11% had overweight or obesity. In multivariable analyses, rapid weight gain (RWG) during 0-6 months (OR: 1.90, 95% CI: 1.23–2.95, p=0.004), maternal pre-pregnancy BMI (1.06, 1.01–1.11, p=0.019) and paternal BMI (1.11, 1.01–1.21, p=0.028) were associated with WHtR_SDS ≥ 1. RWG during 0-6 months (2.53, 1.53–4.20, p<0.001), 6-12 months (2.82, 1.37–5.79, p=0.005), and maternal pre-pregnancy BMI (1.11, 1.06–1.17, p<0.001) were associated with overweight or obesity.

Conclusions: Early risk factors, including rapid weight gain, are associated with increased WHtRSDS and overweight or obesity at 5 years of age. Preventive interventions should target early RWG and parental overweight and obesity.