DOI: 10.1097/01.aoa.0000366990.12697.71

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Issn Print: 0275-665X

Publication Date: 2010/03/01


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Tocolytics and Preterm Labor

A. Carlin; J. Norman; S. Cole; R. Smith

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Author Information: Department of Obstetrics and Gynaecology, Mother and Babies Research Centre, John Hunter Hospital

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Excerpt

Preterm labor remains the primary cause of perinatal morbidity and mortality in the developed world, and the rates are rising. The use of tocolytic drugs can delay delivery up to 48 hours, yet it is unclear whether it improves neonatal outcome. Owing to the lack of evidence, the Royal College of Obstetricians and Gynaecologists guidelines conclude that “it is reasonable not to use tocolytic drugs.” Still, several tocolytics (β agonists, atosiban, indomethacin, and nifedipine) are commonly used worldwide, with no consensus as to which drug is best. Nifedipine has not been studied for use as a tocolytic in placebo-controlled trials, but has been found in some studies to be more effective at delaying delivery than β agonists and been associated with improved neonatal outcomes. The other 3 agents all delay delivery compared with placebo, but none has been shown to improve neonatal outcomes.
A recent study by de Heus et al1 assessed maternal complications with tocolysis and suggested the use of drug therapy is relatively safe. Adverse effects were recorded in 1920 consecutive women given tocolytic drugs in the Netherlands and Belgium over an 18-month period. Agents used most often were atosiban (42% of cases), nifedipine (34%), β agonists (14%), and indomethacin (8%). The overall incidence of adverse effects was reassuringly low; but there were dangers in using multidrug regimens (which have no proven benefits), with 4 women requiring intensive care who received such therapy (3 included β agonists). Such regimens, however, need a thorough case analysis to guide future research. As in other studies, the β agonists had a higher incidence of serious adverse reactions (1.7%) than nifedipine (0.9%) and atosiban (0%). Hypotension was the most serious adverse reaction with nifedipine, but no case required treatment and no episodes of fetal compromise occurred. These findings suggest that there is little justification for using β agonists. Although atosiban had the safest maternal profile, it has not shown improvement in fetal outcomes and is more expensive than nefedipine. This review did not answer the primary question of whether tocolysis should be used at all, as beneficial neonatal effects have not been shown.
The study reminds us that the routine use of tocolysis should be questioned. The authors suggest that a randomized, controlled trial comparing nifedipine and atosiban is needed, including a placebo arm.

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