LONG-TERM MAGNESIUM-SULFATE TOCOLYSIS AND MATERNAL OSTEOPOROSIS IN A TRIPLET PREGNANCY - A CASE-REPORT

Prolonged infusion of magnesium sulfate has been used for the treatmen t of refractory preterm labor. Long-term magnesium sulfate tocolytic t herapy either alone or in combination with other tocolytic agents has been reported to be safe and effective with minimal maternal side effe cts. There has been only one previous report of a disturbance in mater nal calcium homeostasis, which included decreased distal radius bone d ensity and hypercalciuria as a result of prolonged magnesium sulfate i nfusion. This article reports the first case of bilateral fracture of the calcanei in the postpartum period secondary to osteoporosis associ ated with prolonged magnesium sulfate tocolysis and bed rest. A 35-yea r-old white female with a triplet pregnancy of 25 weeks' gestation was admitted in preterm labor. Bed rest, intravenous magnesium sulfate to colysis, and intermittent subcutaneous terbutaline were necessary to m aintain uterine quiescence for 65 days. The patient received weekly be tamethasone for 6 weeks for the acceleration of fetal lung maturation. Daily prenatal multivitamins and low-dose subcutaneous heparin for th romboprophylaxis were given. Efforts at tocolysis were ultimately not successful and the patient underwent a cesarean section delivery at 34 2/7 weeks' gestation. The patient's postoperative course was complica ted by osteoporosis and bilateral stress fractures of the calcanei. Th is case report demonstrates that stress fractures secondary to osteopo rosis may be associated with prolonged magnesium sulfate therapy and b ed rest in higher order multiple pregnancy. Other possible contributin g factors to osteoporosis include heparin thromboprophylaxis and subop timal calcium supplementation. Therefore, in circumstances of prolonge d bed rest and magnesium sulfate tocolysis, additional daily calcium s upplementation would be well advised.