RESEARCH ARTICLE Contribution of prepregna a

Background Low or high prepregnancy body mass index (BMI) and in-adequate or excess gestational weight gain (GWG) are linked to an increased risk of adverse neonatal outcomes. Overweight and obese BMI and excess GWG have been associated with large-for-gestational age (LGA) infants, preterm birth (PTB) and stillbirth while underweight BMI and low GWG have been associated with small-for-gestational age (SGA) infants and PTB [1-6]. Although elevated individual-level risks have been documented in numerous studies, less is known about population-level ef-fects of both BMI and GWG on neonatal outcomes. Population-level effects can be measured using popula-tion attributable fractions (PAFs), which reflect the in-creased risk conferred by a particular determinant and its prevalence in the population. The PAF provides a hypo