[Study on the relationship between leptin and neonatal weight and the expression of leptin in placenta]

To investigate the relationship between the leptin level and neonatal weight and the expression of leptin in placenta.

The concentrations of leptin in 100 maternal blood and umbilical blood of the term pregnant women were examined by radioimmunoassay (RIA). According to the neonatal weight to divide into the large for gestational age (LGA) group 19 cases, the appropriate for gestational age (AGA) group 65 cases, the small for gestational age (SGA) 16 cases. The level of leptin mRNA in 41 placental tissue was examined by Reverse transcription-polymerase chain reaction (RT-PCR).

(1) The expression level of leptin mRNA in placenta was 0.97 +/- 0.04, which was positively related to the neonatal weight significantly (r = 0.43, P < 0.01). The expression level of the LGA group (1.01 +/- 0.03) was significantly higher than the AGA group (0.97 +/- 0.02), (P < 0.01). The expression level of the SGA group (0.93 +/- 0.03) was significantly lower than AGA group, (P < 0.01). (2) The concentration of leptin in maternal blood was (14.22 +/- 7.66) micrograms/L, which was not related to the neonatal weight (r = 0.11, P > 0.05). (3) The concentration of leptin in umbilical blood was (7.58 +/- 5.15) micrograms/L, which was positively related to the neonatal weight (r = 0.57, P < 0.01). The concentration of leptin of LGA group was significantly higher than that of AGA group, which was (7.40 +/- 4.45) micrograms/L (P < 0.01). The concentration of leptin of SGA group was (2.79 +/- 1.54) micrograms/L, significantly lower than that of AGA group, (P < 0.01).

The level of leptin in umbilical blood and placenta is closely related to the growth state of fetus. The level of leptin in maternal blood is not related to the neonatal weight. The placenta of pregnant woman is an important resource of leptin.