Leptin secretion to both the maternal and fetal circulation in the ex vivo perfused human term placenta

The contribution of placental leptin, if any, to both the fetal and maternal circulation and its role in pregnancy remains to be determined. In an experiment to investigate this, 27 placentae from term pregnancies were perfused ex vivo (gestational age=39.5 s.d. 1.2; range=38-42 weeks: fetal weight=3285 s.d. 482; range=2480-4420; birthweight centile range=4th to the 98th) at both the maternal and fetal interface. Placental leptin was exported into both the maternal and fetal circulations. The log leptin production by the maternal side of the placenta was significantly greater (P=0.001) than that for the fetal side (5.193 s.d.1.049 versus 4.387 s.d. 0.768 ng/placenta/min), There was no significant relationship between maternal and fetal log leptin production and maternal body mass index, birthweight, birthweight centile, ponderal index or gestational age or with cord blood pO(2), pCO(2) and pH. There was however, a significant increase in the maternal log leptin production with increasing fetal to placental weight ratio (P=0.0171 r(2)=20.7 per cent) but no corresponding relationship for fetal leptin production. It is proposed that such a mechanism would allow the placenta to modulate fat supply to the fetus in response to the fetal demand relative to placental supply.