Premature Birth is an Independent Risk Factor for Early Adiposity Rebound: Longitudinal Analysis of BMI Data from Birth to 7 Years

Adiposity rebound (AR) refers to the second rise of the body mass index (BMI) curve that usually occurs physiologically between five and seven years of age. AR timing has a great impact on patients' health, since early adiposity rebound (EAR) is associated with the development of metabolic syndrome later in life. We aimed to investigate the prevalence of EAR in a cohort of inborn preterm infants admitted to the Neonatal Intensive Care Section of the Policlinico University Hospital of Bari, Italy. Secondarily, we assessed whether some determinants such as (1) gender; (2) delivery mode; (3) birth weight and classification into small, normal, or large for gestational age; (4) type of feeding; (5) breastfeeding duration; (6) timing of introduction of solid food; (7) parental education; and (8) parental pre-pregnancy body mass index (BMI) influenced EAR in this cohort. The tertiary aim was to evaluate the prevalence of obesity or being overweight at seven years of age in children according to early versus timely AR. This is a prospective, population-based longitudinal study conducted at the Neonatal Intensive Care Section of the Policlinico University Hospital of Bari, Italy. Inborn preterm infants admitted to the neonatal ward between 2009 and 2011 were eligible. Enrolled preterm infants were evaluated at birth and at 1, 3, 6, 9, 12, 15, 18, and 24 months and 3, 4, 5, 6, and 7 years of 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. Of the 250 preterm newborns included, 100 completed the seven-year follow-up and entered the final analysis, 138 were lost during the seven-year follow-up, and in 12 cases parents withdrew over the course of the study. The prevalence of EAR in our cohort of preterm newborns was 54% at seven years of age. Early adiposity rebound was associated with being large for gestational age (LGA) at birth. No other factors were associated with EAR. Early adiposity rebounders had a significantly higher BMI at seven 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 being overweight at seven years of age in children with early or timely AR (29% vs. 14%, p = 0.202). Ex-preterm infants have an increased risk of EAR. Since EAR may lead to long-term detrimental health effects with the onset of various chronic diseases (e.g., obesity, metabolic syndrome, etc.), healthcare providers should be prepared to counteract its occurrence, especially in delicate sub-populations of infants.