Timing of Complementary Feeding in Preterm Infants is not Associated with Early Adiposity Rebound: Longitudinal Analysis of BMI Data from Birth to 7 Years

Background: Adiposity rebound (AR) refers to the second rise of the BMI curve that usually occurs physiologically between 5 and 7 years of age. AR timing has a great impact on children´s health, being the early adiposity rebound (EAR) associated with the development of metabolic disease later in life. Aim: We aimed to investigate the prevalence of EAR in a cohort of preterm newborns. Secondary outcomes evaluated if some determinants such as (1) gender (male/female), (2) type of delivery (caesarean/vaginal), (3) birth weight (SGA/NGA/LGA), (4) type of feeding (5) duration of breastfeeding, (6) timing of introduction of solid food, (7) parental education and (8) parental pre-pregnancy BMI can influence EAR in this cohort. Tertiary aim was to evaluate the prevalence of obesity or overweight at 7 years of age in children according to early versus timely AR. Methods: This is a perspective, population-based longitudinal study, where infants born preterm were evaluated at birth and at 1, 3, 6, 9, 12, 15, 18, 24 months and 3, 4, 5, 6, 7 years of gestational-corrected age. Weight and height data were analyzed, and BMI was calculated. AR was assessed in the growth trajectory in a body mass index (BMI) plot. Results: Of the 250 preterm newborns included, 100 completed the 7 years follow-up and entered in the final analysis. The prevalence of EAR in our cohort of preterm newborns was 54%. EAR was associated with being LGA at birth. No other factors were associated to EAR. Early adiposity rebounders have a significant higher BMI at 7 years compared to children with timely AR (17.2 ±2.7 vs 15.6 ± 2.05, p=0.021). No significant differences were found in the prevalence of obesity or overweight at 7 years of age in children with early or timely AR (29% vs 14% p=0.202). Conclusions: Clinical management of preterm infants should focus on reducing excess weight gain to prevent long-term metabolic risk. Others neonatal factors are not associated to an higher risk of EAR.