Study of Doppler indices of umbilical artery and middle cerebral artery in pregnancies at and beyond forty weeks of gestation

Background: The optimal management of pregnancies beyond date is still debated. Prolonged pregnancies carry risk to the fetus and routine induction increases the rate of primary cesarean section. Hence as there is evidence that placental reserve diminishes beyond term this study was conducted to know the effect of advanced gestation on Doppler indices and its correlation with perinatal outcome. Methods: This prospective study was conducted on 80 pregnant women who are at or beyond 40 weeks of gestation. Doppler indices of umbilical artery and middle cerebral artery were taken. Data were analyzed with obstetrics and perinatal outcome. Results: Umbilical artery mean RI increased with gestational age (p=0.003). There was no significant difference in PI and S/D ratio in different gestational age groups. Middle cerebral artery Doppler indices did not show any significant difference in different gestational age groups. In abnormal Doppler group, perinatal outcome was also not significantly different, but neonatal intensive care unit admission was increased, which was statistically significant (p=0.007). Conclusions: Vascular resistance in the umbilical artery and middle cerebral artery does not change abruptly when gestation exceeds 280 days. It also cannot be taken as the sole method of fetal surveillance when date is crossed.