RESUMEN
BACKGROUND: The safest delivery mode of extremely preterm breech singletons is unknown. OBJECTIVES: To determine safest delivery mode of actively resuscitated extremely preterm breech singletons. SEARCH STRATEGY: We searched Cochrane CENTRAL, MEDLINE, EMBASE, CINAHL and ClinicalTrials.gov from January 1994 to May 2017. SELECTION CRITERIA: We included studies comparing outcomes by delivery mode in actively resuscitated breech infants between 23+0 and 27+6 weeks. DATA COLLECTION AND ANALYSIS: We synthesised data using random effects, generated odds ratios, 95% confidence intervals and number-needed-to-treat (NNT). Our primary outcomes were death (neonatal, before discharge, or by 6 months) and severe intraventricular haemorrhage (grades III/IV), stratified by gestational age (23+0 -24+6 , 25+0 -26+6 , 27+0 -27+6 weeks). MAIN RESULTS: We included 15 studies with 12 335 infants. We found that caesarean section was associated with a 41% decrease in odds of death between 23+0 and 27+6 weeks [odds ratio (OR) 0.59, 95% CI 0.36-0.95, NNT 8], with the greatest decrease at 23+0 -24+6 weeks (OR 0.58, 95% CI 0.44-0.75, NNT 7). The OR at 25+0 -26+6 and 27+0 -27+6 weeks were 0.72 (95% CI 0.34-1.52) and 2.04 (95% CI 0.20-20.62), respectively. We found that caesarean section was associated with 49% decrease in odds of severe intraventricular haemorrhage between 23+0 and 27+6 weeks (OR 0.51, 95% CI 0.29-0.91, NNT 12), whereas the OR at 25+0 -26+6 and 27+0 -27+6 was 0.29 (95% CI 0.07-1.12) and 0.91 (95% CI 0.27-3.05), respectively. CONCLUSIONS: Caesarean section was associated with reductions in the odds of death by 41% and of severe intraventricular haemorrhage by 49% in actively resuscitated breech singletons < 28 weeks of gestation. The data are mostly observational, which may be inherently biased, and scarce on other morbidities, necessitating thorough discussion between parents and clinicians. TWEETABLE ABSTRACT: Caesarean section associated with lower odds of death and severe intraventricular haemorrhage in actively resuscitated breech singletons <28 weeks.