EFFECT OF BIRTH-WEIGHT AND MATERNAL SMOKING ON CORD-BLOOD LEPTIN CONCENTRATIONS OF FULL-TERM AND PRETERM NEWBORNS

Prematurity, maternal smoking, and low birth weight each result in neu roendocrine dysfunction and increased perinatal morbidity and mortalit y. Leptin, an adipocyte-secreted protein, has provided the first physi ological link to the regulatory system controlling starvation-induced neuroendocrine changes in rodents. This study investigated whether lep tin concentrations were detectable in cord blood of newborns, and asse ssed the effect of birth weight, prematurity, and maternal smoking on cord blood leptin concentrations. Fifty consecutively enrolled full-te rm and 12 preterm newborns born to mothers who smoked during pregnancy were compared to 50 full-term and 12 preterm newborns born to parents who were nonsmokers. RIA for leptin was performed using cord blood sa mples collected immediately after birth. Leptin concentrations were de tectable in newborns and correlated positively with obesity (full-term , r = 0.30, P < 0.01; preterm, r = 0.47, P < 0.05). Maternal smoking d uring pregnancy was associated with decreased leptin concentrations in the cord blood of both full-term and preterm newborns. This effect wa s independent of obesity (full-term newborns: 5.25 +/- 2.48 vs. 4.21 /- 2.71 ng/ml, P = 0.01) and was more pronounced in premature newborns (5.67 +/- 3.6 us. 2.46 +/- 2.03, P = 0.02), and its magnitude in full -term newborns was directly related to the reported number of cigarett es the mothers of the full-term newborns smoked per day (r = -0.438, P < 0.001). Thus, low birth weight and maternal smoking are both associ ated with decreased leptin concentrations, and these effects are more pronounced in premature newborns. Future studies will be needed to det ermine whether administration of leptin might reverse the neuroendocri ne dysfunction caused by maternal smoking.