Growth trajectory during the first 1000 days and later overweight in very preterm infants

Objective To identify the characteristics of early life growth associated with later overweight or obesity (OWO) in very preterm population. Design Length, weight and body mass index (BMI) were prospectively recorded from three prospective, population-based cohorts with 5 years (Loire Infant Follow-up Team (LIFT), EPIPAGE2 (Etude EPIdemiologique sur les Petits Ages GEstationnels 2)) and 15 years (EPIPAGEADO, Etude EPIdemiologique sur les Petits Ages GEstationnels-Adolescents) of follow-up. Missing data were imputed. Setting Regional (LIFT), national (EPIPAGE2) and multiregional (EPIPAGEADO) cohorts in France. Patients Eligible infants born before 33 weeks of gestation in 1997 (EPIPAGEADO), between 2003 and 2014 (LIFT), and in 2011 (EPIPAGE2). Main outcome measures OWO was determined as BMI Z-score >85th percentile of the WHO reference curves at 5 years (LIFT, EPIPAGE2) and 15 years (EPIPAGEADO). Results In EPIPAGEADO, LIFT and EPIPAGE2, BMI Z-scores were known for 302 adolescents, 1016 children and 2022 children, respectively. In EPIPAGEADO, OWO was observed in 42 (13.9%, 95% CI 10.5 to 18.3) adolescents. In multivariable models, birthweight Z-score, increase in weight Z-score during neonatal hospital stay and increase in BMI between discharge and at 2 years of corrected age were positively associated with OWO at 15 years (adjusted OR (aOR)=3.65, 95% CI 1.36 to 9.76; aOR=3.82, 95% CI 1.42 to 10.3; and aOR=2.55, 95% CI 1.72 to 3.78, respectively, by Z-score), but change in length Z-score during neonatal hospital stay was negatively associated (aOR=0.41, 95% CI 0.21 to 0.78, p=0.007). These four associations with OWO assessed at 5 years were confirmed in the LIFT and EPIPAGE2 cohorts. Conclusions Change in length Z-score during hospitalisation, a putative proxy of quality of neonatal growth, was negatively associated with risk of later OWO when change in BMI between discharge and at 2 years was included in the multivariable model. Former very preterm born children that are overweight, underweight or normal at 5 or 15 years already had significant different BMI Z-scores by 2 years of age. Change in length Z-score during NICU stay might have a protective effect against later overweight or obesity.