To investigate placental leptin production in placental insufficiency, placental leptin production was measured in women with severe preeclampsia (group 1) and in normotensive pregnancies associated with intrauterine growth restriction (group 2), compared to controls (group 3). Placental leptin content was increased 3-fold in group 1 compared to group 2 (192.5.1 ± 39.5 vs. 67.8 ± 10.6 ng/g) and 8-fold in group 1 compared to group 3 (192.5.1 ± 39.5 vs. 25.4 ± 6.9 ng/g). Placental leptin content was positively correlated with maternal leptin/BMI ratio (r = 0.62) and the resistance index of the umbilical artery (r = 0.60). These data demonstrate that placental insufficiency is associated with a dramatic increase in placental leptin production. This results in a rise in maternal leptinemia that may be taken as an early index of placental dysfunction.