Acute tocolysis for intrapartum non-reassuring fetal status: how often does it prevent cesarean delivery? A systematic review and meta-analysis of randomized controlled trials

Objective: The aim of this systematic review and meta-analysis of randomized controlled trials (RCTs) was to evaluate the effectiveness of intrapartum acute tocolysis for non-reassuring fetal heart rate tracing (NRFHT) in decreasing the incidence of cesarean delivery (CD). Secondary outcomes were considered other modes of delivery than CD, successful acute tocolysis, time to the delivery interval, and short-term perinatal outcomes. Data sources: Searches were performed in MEDLINE/PubMed, EMBASE, Scopus, the Cochrane Central Register of Controlled Trials and Reviews, ClinicalTrials.gov, and the International Clinical Trials Registry Platform (ICTRP) from the inception of each database until February 2022. Study eligibility criteria: Selection criteria included RCTs of laboring singleton gestations randomized to receive intrapartum acute tocolysis for NRFHT, as defined by the original trial. Study appraisal and synthesis methods: All analyses were done using an intention-to-treat approach, evaluating women according to the treatment group to which they were randomly allocated in the original trials. A frequentist network-meta-analysis was performed. Results: Four randomized clinical trials were eligible, including 605 patients with NRFHT and singleton gestation at a gestational age more than 32 weeks. The CD rate was similar in patients managed with different types of acute tocolysis. Acute tocolysis, compared with emergency delivery, was associated with improved neonatal acid-base status (notably decreasing the prevalence of base deficit > 12 mmol/L (beta-2 agonists OR 0.61 CI.95 0.37-0.99) and the rate of neonatal intensive care unit admission (beta-2 agonists OR 0.42 CI.95 0.22-0.78)) and with an increase in the time interval to delivery (beta-2 agonists MD 17.62 minutes CI.95 15.66-19.58); there was no reduction of the CD rate showing an increased rate in atosiban and beta-2 agonists. Conclusions: The CD rate was not reduced by acute tocolysis when used for NRFHT during labor. Acute tocolysis is associated with improved short-term fetal outcomes and safely increases the interval to delivery