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

The contribution of placental leptin, if any, to both the fetal and materna l circulation and its role in pregnancy remains to be determined. In an exp eriment to investigate this, 27 placentae from term pregnancies were perfus ed 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 int o both the maternal and fetal circulations. The log leptin production by th e maternal side of the placenta was significantly greater (P=0.001) than th at 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 ce ntile, ponderal index or gestational age or with cord blood pO(2), pCO(2) a nd 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 productio n. It is proposed that such a mechanism would allow the placenta to modulat e fat supply to the fetus in response to the fetal demand relative to place ntal supply.