Neonatal acid-base status before and after discontinuing routine left uterine displacement for elective cesarean delivery: a retrospective cohort study (2014–2017)

Background: Maintaining left uterine displacement during cesarean delivery has been a decades-long recommendation to mitigate aortocaval compression. We abandoned the practice at our institution following the publication in 2017 of our study showing that maternal supine position did not impair neonatal acid-base status compared with 15 degrees left tilt, when maternal systolic blood pressure was maintained with a crystalloid coload and prophylactic phenylephrine infusion. We hypothesized that there would be no difference in mean umbilical artery base excess between neonates delivered by elective cesarean section with spinal anesthesia during the periods before and after our change in practice. Methods: Maternal demographics and neonatal outcomes were obtained by retrospective review of electronic health records in 2014 (‘with tilt’) and 2017 (‘no tilt’). Cases with elective cesarean delivery of singleton pregnancies at term with spinal anesthesia were selected consecutively in each year. Routine practice included crystalloid coloading and prophylactic phenylephrine infusion targeted at maintaining maternal baseline systolic blood pressure. The primary outcome was mean umbilical artery base excess, analyzed using an unpaired t-test for two groups. Results: There were no differences in umbilical artery or vein base excess or pH ‘with tilt’ (n=201) vs. ‘no tilt’ (n=202). There was also no significant difference between groups in the number of outliers with respect to neonatal umbilical artery base excess, pH, Apgar scores or need for resuscitation. Conclusion: No tilt of surgical table in elective cesarean delivery cases with spinal anesthesia did not affect neonatal acid-base status compared with a historical cohort when maternal tilt was routine.