Maternal Magnesium Level Effect on Preterm Labor Treatment

Objectives: This study intended to compare the serum magnesium level in women with preterm labor, with its level in women with normal pregnancy of the same age, and assess the relationship between serum magnesium level and response to magnesium sulfate (MgSO4). Materials and Methods: Forty women aged 18-40, with gestational age of 26-32 weeks and signs of preterm labor, and 40 women in similar age and gestational age with normal pregnancy were included in this study. Case group received betamethasone 12 mg in 2 separate doses with 24-hour interval. MgSO4 was administrated (in dose of 4 mg), and continued by 2 mg/h. Once the tocolytic therapy goal was achieved, the administration of MgSO4 continued for an additional 12-hour. Results: The mean age, gestational age, gravidity, parity, number of live born children, number of dead children, miscarriage, and molar pregnancy were similar in 2 groups. The mean of serum magnesium level showed a significant difference between 2 groups. In the case group, 27 patients showed positive therapeutic response to MgSO4; the difference between the mean of serum magnesium level in these 27 patients and the other 13 patients who did not respond well was significant. The serum magnesium level < 1.85 mg/dL as a cut-off point had 85% sensitivity and 78% specificity with CI = 0.75-0.97 in predicting response to MgSO4 in the case group. Conclusion: Serum magnesium level can be used as a predictive tool for preterm labor. It can help in preterm labor in selecting patients who benefit from MgSO4 as a tocolytic agent. Magnesium supplementation may be helpful in patients with decreased serum magnesium level to prevent preterm labor.