Intended for healthcare professionals


Tocolytics: do they actually work?

BMJ 2012; 345 doi: (Published 09 October 2012) Cite this as: BMJ 2012;345:e6531
  1. Zarko Alfirevic, professor of fetal and maternal medicine
  1. 1Department of Women’s and Children’s Health, University of Liverpool, Liverpool Women’s Hospital, Liverpool L8 7SS, UK
  1. zarko{at}

Never mind “which one works?” We still don’t know if delaying delivery is safe

In a linked research paper (doi:10.1136/bmj.e6226), Haas and colleagues assessed the relative effectiveness of various tocolytic drugs aimed at preventing preterm birth.1 Being born too early may have serious detrimental effects on health. It is hardly surprising that extremely preterm children, born before 26 weeks’ gestation, who survive to school age have significantly lower scores for cognitive ability, reading, and mathematics.2 However, even babies born a few weeks before term are more likely to underperform on most measures of general health than their peers born at term.3 With an estimated 14.9 million babies born preterm each year (11.1% of all live births worldwide), the burden of preterm births on families and healthcare systems in high income and low income countries is considerable.4 It is important to remember that some preterm births are iatrogenic. They are a consequence of labour induction or prelabour caesarean sections, which are often life saving interventions for mother and baby, particularly in severe pre-eclampsia, intrauterine growth restriction, or placental abruption. Such iatrogenic preterm births should be …

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