Benefits of tocolytics outweigh any risks linked with unwanted side effects, study finds

Women around the world should be able to access the best medical treatments that help to delay preterm births and improve neonatal outcomes, new research suggests.

A new paper published in Cochrane Reviews today (Thurs 4 Aug – USA / Fri 5 Aug – UK) looked at data from 122 clinical trials to create a league table of drugs that delay birth, called tocolytics, about their effectiveness and side effects. Researchers from the University of Birmingham and World Health Organization reviewed 122 randomised trials, published between 1966 and 2021, involving 13,697 women and conducted in 39 countries including high, middle and low-income states.

Women benefitted from all preterm delay treatments included in the meta-analysis of studies, although the research team noted that the effectiveness of different drugs was less clear in some of the studies considered. The team also looked at the side effects of different drugs and combinations, including the likelihood of having to stop treatment.

The team have bought together the evidence on the benefits as well as the harms of these treatments (compared to no treatment or placebo), to arm clinicians and policy makers around with world with the information to decide upon the best treatment for the women in their care in their specific setting.

The findings show that the benefits of these drugs outweigh any risks associated with unwanted side effects. These treatments are leading to a significant reduction in the number of deadly preterm births, and we now need to further understand the effectiveness of tocolytics for specific groups depending on pregnancy length."

Dr Amie Wilson, Research Fellow, Global Maternal Health, University of Birmingham

"Our previous research has led to the improvement of guidelines for use of tocolysis drug use to delay preterm birth in the UK. Knowing that this paper helped to inform the forthcoming recommendations of the World Health Organization on the use of tocolytics, we hope that many more women around the globe will have access to these drugs, and have healthier births."

Dr Victoria Hodgetts Morton, NIHR Clinical Lecturer in Obstetrics at the University of Birmingham and co-author of the paper said:

"Preterm birth is the most common reason why a newborn baby may die, and the leading cause of death in children under five years of age.

"Tocolytics aim to delay preterm birth and allow time for the women to receive medicines that can help with baby's breathing and feeding if born preterm, and medicines that lower the chance of cerebral palsy of the infant. Crucially, a short delay in preterm birth can enable women to reach specialist care."