Maternal Morbidity Tied to Prolonged MgSO4 Tocolysis


RENO, NEV. — Increased maternal morbidity is significantly associated with magnesium sulfate tocolysis that lasts longer than 48 hours, a retrospective study has demonstrated.

Investigators compared 78 women who received MgSO4 tocolysis for longer than 48 hours with 77 women who received MgSO4 tocolysis for 48 hours or less. Women who received prolonged tocolysis were significantly more likely to have at least one adverse event (56.4% vs. 28.5%).

The most common adverse events were chest tightness, pulmonary edema, and visual disturbances, investigators wrote in a poster presentation at the annual meeting of the Society for Maternal-Fetal Medicine.

Babies born to the two groups of mothers had similar Apgar scores, hypotonia, and neonatal mortality rates. But babies born to women who underwent prolonged tocolysis had significantly higher magnesium levels, averaging 3.6 mg/dL, compared with 2.8 mg/dL for babies born to control women, reported Anwar Nassar, M.D., and colleagues at the American University of Beirut (Lebanon).

In addition, three infants born to mothers who had received large amounts of MgSO4 showed radiolucent bones and metaphyseal widening, evidence of abnormal bone mineralization.

“Given the scarcity of evidence of its effectiveness as a tocolytic and the potential of significant adverse effects on the mother and neonate, aggressive attempts at prolonging pregnancy with intravenous magnesium sulfate are unjustifiable,” the investigators wrote.

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