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

Objective: To examine the influence of antenatally administered magnesium s ulfate (MgSO4 and ritodrine on cerebral blood flow and systemic hemodynamic s 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 a rteriosus 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 we re 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 cereb ral blood flow velocity or resistance, but was associated with decreased (p < .05) perfusion pressure and blood flow in the anterior cerebral artery a nd internal carotid artery during the first day of life. Systolic blood pre ssure and pulse pressure were also lower (p < .05) during the whole study p eriod in the MgSO4-exposed infants when compared with the controls. Materna l ritodrine treatment, on the other hand, had no consistent effects on eith er neonatal cerebral or systemic hemodynamics. Conclusions: Our data indicate that maternal MgSO4 treatment, in contrast t o antenatal ritodrine, is associated with lowered cerebral perfusion in pre term infants on the first day of life.