Fetal platelet consumption: a feature of placental insufficiency.

The involvement of fetal platelets in placental insufficiency was investigated. Platelet life span and the rate of platelet turnover were measured by a novel technique in fetuses with moderate and severe placental insufficiency and in controls. This procedure involves the measurement of platelet count and concentration of free glycocalicin in plasma. Placental insufficiency was defined by antenatal Doppler ultrasound analysis of the umbilical artery waveform, which was used to categorize the subjects according to whether their systolic-diastolic ratios were normal, moderately raised, or severely raised. Mean platelet life span in fetuses affected by placental insufficiency was only 60% of the normal fetal platelet life span (P less than .001). In addition, affected fetuses had a higher rate of platelet turnover, reflected in an elevated plasma glycocalicin concentration (4.06 +/- 0.19 versus 3.28 +/- 0.15 microgram/mL for severe placental insufficiency and control fetuses, respectively; P less than .01). Platelet life span did not differ between the moderate and severe placental insufficiency groups. We hypothesize that the observed changes in platelet life span and turnover result from increased platelet activation, which plays a role in the development of placental insufficiency.