Background: Doppler studies are being used routinely and with no specific indication. There is no evidence about the clinical significance of pulsatility index (PI) below 5th centile in the middle cerebral artery (MCA) in fetuses at third trimester. Objective: To determine perinatal outcomes in fetuses at third trimester with PI<5th centile in the middle cerebral artery (MCA) compared to fetus with normal cerebral Doppler studies. Methods: A retrospective cohort study was designed. We included women pregnant with Doppler studies at third trimester during 2008. We categorized two groups according to the PI in the MCA, below the 5th centile and above the 5th centile. Results: 265 patients met inclusion criteria. Both groups were similar and homogeneous based on their main characteristics. The PI below 5th centile group showed a higher mean gestational age 39.4 vs. 38.9 weeks (p=0.001). However, after categorization in preterm delivery below 37 weeks there was no significant difference (p=0.89). In fetuses with PI<5th centile, 19 (25.7%) cesarean sections were performed due to fetal distress and similarly 42 (22%) cesarean sections were performed in the control group (p=0.51). PI<5th centile was not associated with a 5-min Apgar score below 7 (5.4% vs. 3.1%, p=0.47). Similarly, there was no difference in the admission to neonatal intensive care unit (10.8% vs. 6.3%, p=0.31) between both groups. Conclusions: Fetuses at third trimester with pulsatility index below the 5th centile in the cerebral middle artery Doppler have similar perinatal outcomes compared to fetus with normal cerebral Doppler studies.