Risks and Benefits of Magnesium Sulfate Tocolysis in Preterm Labor (PTL)

Abstract

The U.S. Food and Drug Administration issued a drug safety communication on 05/30/2013 recommending “against prolonged use of magnesium sulfate to stop preterm labor (PTL) due to bone changes in exposed babies.” In September of 2013, The American Congress of Obstetrics and Gynecologists issued Committee Opinion No. 573 “ Magnesium Sulfate Use in Obstetrics” , which supports the short term use of MgSO4 to prolong pregnancy (up to 48 hrs.) to allow for the administration of antenatal corticosteroids.” Are these pronouncements by respected organizations short sighted and will potentially result in more harm than good? The FDA safety communication focuses on bone demineralization (a few cases with fractures) with prolonged administration of MgSO4 (beyond 5–7 days). It cites 18 case reports in the Adverse Event Reporting System with an average duration of magnesium exposure of 9.6 weeks (range 8–12 wks). Other epidemiologic studies showed transient changes in bone density which resolved in the short duration of follow up. Interestingly, the report fails to acknowledge the fact that these 18 fetuses were in danger of PTD and the pregnancy was prolonged by 9.6 weeks (e.g. extending 25 weeks to 34.6 wks), thus significantly reducing mortality and morbidity. Evidence does support the efficacy of MgSO4 as a tocolytic medication. The decision to use magnesium, the dosage to administer, the duration of use, and alternative therapies are physician judgments. These decisions should be made based on a reasonable assessment of the risks of the clinical situation (PTL) and the treatments available versus the benefits of significantly prolonging pregnancy.

Antenatal magnesium sulphate and adverse neonatal outcomes: A systematic review and meta-analysis

“…The findings of this review are reassuring and can be considered in conjunction with those from relevant reviews demonstrating a clear benefit of antenatal magnesium sulphate [1,2,4], and current international clinical practice guideline recommendations [3,7]. Our review findings of possible adverse outcomes with long-term, high-dose use for tocolysis have implications for settings with continued use for this indication [8] in spite of the absence of benefit shown in systematic reviews and international guidance [7–9].…”

“…Systematic reviews and clinical practice guidelines support its use when given for maternal neuroprotection in pre-eclampsia or eclampsia [1–3] and for neuroprotection of the fetus in women at risk of preterm birth (for cerebral palsy prevention) [4–7]. Despite continued use in some countries [8], available evidence does not support its role in preventing preterm birth in women with, or following, threatened preterm labour (for tocolysis) [7,9].…”

A comparative study of magnesium sulphate and isoxsuprine as a tocolytic in preterm labour

“…In babies bone demineralization seen which was reversible. 9 Mahajan et al showed successful tocolysis in 82% cases and 66% cases with magnesium sulphate and isoxsuprine respectively. Magnesium sulphate was able to maintain successful tocolysis for 7 days in 74% cases as compared to 50% in patients receiving isoxsupine.…”

In vitro effects of citral on the human myometrium: Potential adjunct therapy to prevent preterm births

“…Basically, tocolytic drugs are the main option for the treatment of preterm birth. Unfortunately, they have been frequently associated with low efficacy and adverse reactions (Clouqueur et al, 2015;Elliott, Morrison, & Bofill, 2016;Guden et al, 2016). For that reason, the development of new drugs and/or the discovery of medicinal plants for the treatment of PTB is an area of growing interest.…”