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Journal of Pregnancy
Volume 2011, Article ID 965060, 6 pages
Research Article

Magnesium Sulfate as a Second-Line Tocolytic Agent for Preterm Labor: A Randomized Controlled Trial in Kyushu Island

1Department of Obstetrics and Gynecology, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan
2Department of Obstetrics and Gynecology, National Hospital Organization Nagasaki Medical Center, Nagasaki 856-8562, Japan
3Department of Obstetrics and Gynecology, Fukuoka University, Fukuoka 814-0180, Japan

Received 14 October 2010; Revised 6 April 2011; Accepted 27 April 2011

Academic Editor: Sinuhe Hahn

Copyright © 2011 Yasuyuki Kawagoe et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Objectives. We evaluated the efficacy of magnesium sulfate as a second-line tocolysis for 48 hours. Materials and Methods. A multi-institutional, simple 2-arm randomized controlled trial was performed. Forty-five women at 22 to 34 weeks of gestation were eligible, whose ritodrine did not sufficiently inhibit uterine contractions. After excluding 12 women, 33 were randomly assigned to either magnesium alone or combination (ritodrine and magnesium). The treatment was determined as effective if the frequency of uterine contraction was reduced by 30% at 48 hours of the treatment. Results. After magnesium sulfate infusion, 90% prolonged their pregnancy for >48 hours. Combination therapy was effective in 95% (18/19), which was significantly higher than 50% (7/14) for magnesium alone. Conclusion. This randomized trial revealed that combination therapy significantly reduced uterine contractions, suggesting that adjuvant magnesium with ritodrine is recommended, rather than changing into magnesium alone, when uterine contractions are intractable with ritodrine infusion.