Osteopenic effects of MgSO4 in multiple pregnancies

To describe the effects of prolonged maternal treatment with MgSO4 in infants who were products of multiple pregnancies.

Case series of infants presenting with osteopenia secondary to MgSO4 administration for preterm labor.

Ten premature infants with hypermagnesemia (4.5+/-0.2 mg/dl), hypocalcemia (6.0 +/-0.3 mg/dl), and high serum alkaline phosphatase (574+/-96 U/l) underwent imaging studies that showed diffuse osteopenia of the long bones and probable rib fractures. All mothers had isolated premature labor, for which they were given MgSO4; (average dose 3.66+/-0.08 kg/ pregnancy over 10.0+/-0.5 weeks). On follow-up (to 9 months), all infants had complete or near complete resolution of the osteopenia.

Premature infants who are exposed to large doses of MgSO4, especially those of multiple pregnancies, have an increased risk of developing hypocalcemia, osteopenia, and fractures. Our findings indicate that these infants should be identified at birth and managed prospectively.