Leptin Levels of the Perinatal Period Shape Offspring’s Weight Trajectories through the First Year of Age

Background: Leptin is a hormone regulating lifetime energy homeostasis and metabolism and its concentration is important starting from prenatal life. We aimed to investigate the association of perinatal leptin concentrations with growth trajectories during the first year of life. Methods: Prospective, longitudinal study, measuring leptin concentration in maternal plasma before delivery, cord blood (CB), and mature breast milk and correlating their impact on neonate’s bodyweight from birth to 1 year of age, in 16 full‐term (FT), 16 preterm (PT), and 13 intrauterine growth‐restricted (IUGR) neonates. Results: Maternal leptin concentrations were highest in the PT group, followed by IUGR and FT, with no statistical differences among groups (p = 0.213). CB leptin concentrations were significantly higher in FT compared with PT and IUGR neonates (PT vs. FT; IUGR vs. FT: p < 0.001). Maternal milk leptin concentrations were low, with no difference among groups. Maternal leptin and milk concentrations were negatively associated with all the neonates’ weight changes (p = 0.017 and p = 0.006), while the association with CB leptin was not significant (p = 0.051). Considering each subgroup individually, statistical analysis confirmed the previous results in PT and IUGR infants, with the highest value in the PT subgroup. In addition, this group’s results negatively correlated with CB leptin (p = 0.026) and showed the largest % weight increase. Conclusions: Leptin might play a role in neonatal growth trajectories, characterized by an inverse correlation with maternal plasma and milk. PT infants showed the highest correlation with hormone levels, regardless of source, seeming the most affected group by leptin guidance. Low leptin levels appeared to contribute to critical neonates’ ability to recover a correct body weight at 1 year. An eventual non‐physiological “catch‐up growth” should be monitored, and leptin perinatal levels may be an indicative tool. Further investigations are needed to strengthen the results.