LAUSR

To evaluate associations between pre-pregnancy body mass index (BMI), gestational weight gain (GWG), and postnatal growth in preterm infants. A cohort study of 14,962 births < 32 weeks’ gestation. We used multivariable linear regression to assess associations between maternal BMI or GWG (models stratified by BMI) and infant postnatal growth, defined as the difference between discharge and birth weight Z-scores based on Fenton or INTERGROWTH-21st growth charts. For BMI, obesity class 2 was positively associated with postnatal growth using the Fenton chart. Using INTERGROWTH-21st, inadequate or excessive GWG in women with underweight or obesity class 3 were associated with postnatal growth in different directions. Excessive GWG in women with normal weight was negatively associated with postnatal growth defined by Fenton. Some categories of BMI and GWG were modestly associated with postnatal growth in preterm infants. Results were inconsistent within and between the INTERGROWTH-21st standard and Fenton growth reference.