The outcomes and risk factors of fetal bradycardia associated with external cephalic version.

The objective of this study is to assess the outcomes and risk factors of fetal bradycardia after external cephalic version (ECV). We performed a retrospective study of women who underwent ECV after 35 weeks of gestation in 2010-2016. We assessed the birth outcomes, including umbilical cord artery pH, according to the duration of fetal bradycardia and the risk factors for bradycardia. Among 390 cases, 189 (48.5%) cases showed fetal bradycardia during or immediately after ECV. The duration of fetal bradycardia was <1 min (n = 82, 43.4%), <5 min (n = 168, 88.9%); and <10 min (n = 186, 98.4%). All cases showed a good prognosis. Fetal bradycardia lasting >10 min occurred in three cases; emergency cesarean section was performed in each case, with delivery after 12-4 min of bradycardia. Two of three cases showed low Apgar scores at 5 min, with an umbilical cord arterial pH of <7.1. Lower maternal BMI and a prolonged ECV procedure were significantly associated with bradycardia (p for trend: .016 and .015, respectively). Fetal bradycardia lasting >10 min after ECV was a risk factor for asphyxia. Thus, delivery should be completed within 10 min after bradycardia. A low maternal BMI and a prolonged ECV procedure were risk factors for bradycardia after ECV.