Uterine, Fetal Cerebral Doppler and Oligohydramnios to Predict Abnormal Heart Rate Tracings in Postterm Pregnancies

Inclusion Criteria: * Singleton pregnancy * Gestational age of at least 287 days (41 weeks) * Low risk pregnancy (defined as the absence of maternal or fetal complications other than postterm pregnancy) Exclusion Criteria: * Twin or multiple gestation * Uncertain gestational age * Non vertex presentation * Estimated fetal weight below the 10th percentile for gestational age (Hadlock´s formula) * Fetal macrosomia (estimated fetal weight ≥ 4 Kilos) diagnosed by clinical measurement (Johnson´s technique) or ultrasound measurement (Hadlock´s formula). * Fetal abnormalities found on routine anomaly scan. * Maternal medical disorder (preeclampsia, chronic hypertension, diabetes, lupus, hyperthyroidism) * Prelabour rupture of membranes * Antepartum hemorrhage * Any fetopelvic disproportion that could create dystocia during labor.