MATERNAL MIDDLE CEREBRAL-ARTERY VELOCIMETRY IN NORMAL-PREGNANCY AND POSTPARTUM

Objective To study changes throughout gestation and the puerperium of middle cerebral artery flow velocity waveforms obtained by transcrania l Doppler ultrasound. Design Prospective, observational study. Setting John Radcliffe Maternity Hospital, Oxford, UK. Participants and Metho ds Middle cerebral artery velocities were measured by transcranial Dop pler ultrasound in 25 nonpregnant women, 22 women longitudinally follo wed throughout pregnancy and 21 women serially studied from delivery u ntil the late puerperium. Main outcome measures Transcranial Doppler c hanges in pregnancy and the puerperium. Results The transcranial Doppl er ultrasound measurements showed good reproducibility. Signals from o ne middle cerebral artery could not be obtained in 4.6% of the examina tions, but otherwise readings were similar on both sides. Women in the second half of pregnancy had lower middle cerebral artery mean veloci ties than nonpregnant women. Velocities decreased with advancing gesta tion but increased in the immediate puerperium to levels comparable to those found in nonpregnant women. Conclusions Transcranial Doppler ul trasound is a noninvasive technique suitable for studying maternal cer ebral haemodynamics in pregnancy and postpartum. Middle cerebral arter y mean velocity decreased with advancing gestation and increased to no npregnant values in the immediate puerperium. These physiological chan ges need to be considered when comparing data with measurements taken in abnormal pregnancy states.