Leptin levels at birth and infant growth: the EPOCH study

Objective: To examine the association of cord blood leptin with body mass index (BMI) growth velocity from birth to 12 months of age among infants exposed and not exposed to over-nutrition in utero (defined as maternal overweight/obesity or presence of gestational diabetes). Methods: 185 infants enrolled in the Exploring Perinatal Outcomes among Children study (76 exposed and 109 not exposed) had leptin and insulin measured in cord blood. Longitudinal weight and length measures in the first 12 months of life (average 4 per participant) obtained from medical records were used to compute BMI growth rates. Mixed models were used to examine associations of cord blood leptin with growth. Results: Compared with unexposed infants, those exposed had significantly higher cord blood insulin (8.64 v. 6.97 uU/ml, P<0.01) and leptin levels (8.89 v. 5.92 ng/ml, P=0.05) as well as increased birth weights (3438.04 v. 3306.89 g, P=0.04). There was an inverse relationship between cord leptin levels and BMI growth from birth to 12 months of age (P=0.005); however, exposure to over-nutrition in utero did not significantly modify this association (P=0.59). Conclusion: We provide support of a possible operational feedback mechanism by which lower cord blood leptin levels are associated with faster infant growth in the first year of life. Our data do not tend to support the hypothesis that this mechanism is altered in infants exposed to over-nutrition in utero; however our sample is too small to provide sufficient evidence. Larger epidemiological studies are needed to elucidate the mechanisms responsible for increased propensity for obesity in exposed offspring.