Serum Concentration of Leptin in Pregnant Adolescents Correlated with Gestational Weight Gain, Postpartum Weight Retention and Newborn Weight/Length

Abstract

Introduction: Gestational weight gain is an important modifiable factor known to influence fetal outcomes including birth weight and adiposity. Leptin is normally correlated with adiposity and is also known to increase throughout pregnancy, as the placenta becomes a source of leptin synthesis. Several studies have reported positive correlations between cord blood leptin level and either birthweight or size for gestational age, as well as body mass index (BMI). Objective: To determine the correlation of prenatal leptin concentration in pregnant adolescents with their gestational weight gain, postpartum weight retention, and weight/length of their newborn. Methods: A cohort study was conducted on pregnant Mexican adolescents from Gestational Week 26-28 to three months postpartum (n = 168 mother-child dyads). An anthropometric assessment was made of each pregnant adolescent, and the serum level of leptin and the intake of energy were determined. The newborn was evaluated each month during postpartum. Clinical records were reviewed to obtain sociodemographic data. Bivariate correlations, tests for repeating measurements and logistic regression models were performed. Results: Leptin concentration gradually increased during the third trimester of pregnancy. At Gestation Week 36, leptin level correlated with gestational weight gain. When comparing adolescents that had the lowest and highest concentration of leptin, the former presented a mean of 6 kg less in gestational weight gain (inter-subject leptin concentration, p = 0.001; inter-subject energy intake, p = 0.497). Leptin concentration and gestational weight gain exerted an effect on the weight of the newborn (inter-subject leptin concentration for Week 32, p = 0.024; inter-subject gestational weight gain, p = 0.011). Newborn length was associated with leptin concentration at Week 28 (leptin effect, p = 0.003; effect of gestational weight gain, p = 0.722). Conclusions: Pregnant adolescents with leptin concentration over 20 ng/mL showed a greater gestational weight gain. Leptin concentration correlated with length and weight of the newborn.

Keywords: Leptin; adolescent pregnancy; birth weight; pregestational body mass index gestational; weight gain.

Figure 1

Gestational weight gain (%) according to pregestational BMI.

Figure 2

Leptin and gestational weight gain: (A) tendency of leptin (ng/mL) from 28 to 36 gestational weeks; (*): Gestation Week 28 and 32; (**): Gestation Week 32 and 36; and, (***): Gestation Week 28 and 36 and (B) correlation between gestational weight (kg) and leptin concentration (ng/mL) at Gestation Week 36.

Figure 3

In (A), at Gestation Week 28 p = 0.027, post hoc less vs. excessive p = 0.008; at Gestation Week 32 p = 0.001, post hoc less vs. excessive p = 0.001, adequate vs. excessive p = 0.003; and at Gestation Week 36 p = 0.001, post hoc less vs. excessive p = 0.001, adequate vs. excessive 0.001. In (B), at Gestation Week 28 p = 0.001, post hoc less vs. excessive p = 0.001, adequate vs. excessive p = 0.014; at Gestation Week 32 p = 0.004, post hoc less vs. excessive p = 0.001, adequate vs. excessive p = 0.043; and at Gestation Week 36 p = 0.054, post hoc less vs. excessive p = 0.057, adequate vs. excessive 0.031. Leptin concentrations (ng/mL) at 28, 32 and gestation week 36, according to gestational weight gain, in adolescents according pregestational BMI: (A) low and normal n = 134; and (B) overweight and obese n = 34.

Figure 4

Evolution of serum concentration of maternal leptin (ng/mL) according to gestational weight gain.