Hemodynamic, hematological and hemorrheological evaluation of post-term pregnancy

To evaluate the hemorrheological modifications in post-term pregnant women.

Pregnant women (n = 48) at > 280 days' gestation, were tested on alternate days by nonstress test; ultrasound assessment of amniotic fluid volume, placental grading, hourly measurement of fetal urine production, and maternal fetal Doppler analysis. We further recorded maternal: plasma viscosimetry, red blood cells, hemoglobin, hematocrit, platelet count, mean platelet volume, fibrinogen, antithrombin III, creatinine, uric acid, plasma calcium, hPL, and estriol. We analyzed the last values obtained within 48 hours prior to delivery.

The subjects were divided into Group I (40 wks to 40 wks+3 days; n = 16); Group II (40 wks+4 days to 41 wks; n = 16); Group III (> 41 wks; n = 16). The time-averaged maximum velocity of the fetal descending thoracic aorta was lower at Doppler analysis in Group III (29.0 +/- 3.5 cm/s) than in Group I (34.0 +/- 4.3 cm/s; p < 0.05). A decrease of the middle cerebral/umbilical pulsatility index ratio (1.75 in the Group I vs 1.52 in the Group III; p < 0.05) was shown. Furthermore, the incidence of oligohydramnios; Grannum placental grade III; plasma viscosity and coagulation parameters were significantly higher in Group III patients. The plasma viscosity resulted positively correlated with uric acid, and inversely correlated with fibrinogen, antithrombin III and platelet number values.

From the present data we conclude that post-term pregnancy may mimic a mild 'fetal growth restriction'.