Maternal magnesium sulfate treatment is associated with reduced brain-blood flow perfusion in preterm infants

Objective: To examine the influence of antenatally administered magnesium sulfate (MgSO4 and ritodrine on cerebral blood flow and systemic hemodynamics in preterm infants. Design: Prospective, observational study. Setting: Neonatal intensive care unit of a university central hospital. Patients: Fifty-five preterm infants age < 33 wks of gestation. Interventions. Serial Doppler examinations of the brain circulation, heart rate, systemic blood pressure, and echocardiographic assessment of ductus arteriosus shunting were performed during the first week of life in infants exposed antenatally to maternal MgSO4 (n = 19) or ritodrine treatment (n = 17), and in 19 nonexposed preterm controls. Measurements and Main Results: Cerebral blood flow velocity measurements were obtained from the anterior cerebral artery and internal carotid artery. Perfusion pressure and indices of resistance and blood flow in both vessels were subsequently derived. Maternal MgSO4, had no effect on neonatal cerebral blood flow velocity or resistance, but was associated with decreased (p < .05) perfusion pressure and blood flow in the anterior cerebral artery and internal carotid artery during the first day of life. Systolic blood pressure and pulse pressure were also lower (p < .05) during the whole study period in the MgSO4-exposed infants when compared with the controls. Maternal ritodrine treatment, on the other hand, had no consistent effects on either neonatal cerebral or systemic hemodynamics. Conclusions: Our data indicate that maternal MgSO4 treatment, in contrast to antenatal ritodrine, is associated with lowered cerebral perfusion in preterm infants on the first day of life.