Low leptin concentration in the first gestational trimester is associated with being born small for gestational age: prospective study in Rio de Janeiro, Brazil.

Background: Being born small for gestational age (SGA) is a known risk factor for greater neonatal mortality and disease in later life. Some determinants of the incidence of SGA newborns have been studied but little is known about the role of leptin in the beginning of pregnancy.

Objectives: To investigate the effect of serum leptin concentration in the 1st gestational trimester on the incidence of SGA newborns and to identify other determining factors in the occurrence of SGA.

Methods: Prospective study with 195 pairs of mothers and their children monitored in Rio de Janeiro, Brazil. The dependent variable was SGA newborns, while the independent variables were sociodemographic, reproductive, anthropometric and biochemical variables. Statistical analysis was performed by means of logistic regression.

Results: The incidence of SGA was 11.3% (CI 95%: 7.31-16.46). The results showed that low concentrations (lowest tertile compared to 2nd and 3rd tertiles) of leptin (RR = 5.26; CI 95%: 1.91-9.56), insufficient gestational weight gain (RR = 3.16; CI 95%: 0.98-7.38), low stature (RR = 3.94; CI 95%: 1.22-8.57) and alcohol consumption during gestation (RR = 5.92; CI 95%: 1.44-12.92) were risk factors for SGA.

Conclusions: Lower leptin concentrations were associated with a significant risk for SGA after adjusting for confounding variables. Maternal serum leptin at the beginning of gestation can be used as a marker for the early detection of SGA.