Obstetrical outcomes
The data for obstetrical outcomes were obtained from the M0 data and included the following: gestational age at the time of delivery, the presence or absence of placental abruption, mode of delivery, umbilical artery (UmA) pH, and maternal transfusion. The mode of delivery was categorized into vaginal delivery or cesarean section (CS). In the present study, placental abruption was diagnosed clinically based on the clinical findings of abdominal pain, vaginal bleeding, uterine contractions, fetal distress, and vital signs’ abnormalities at the discretion of the obstetrician in charge. Histological confirmation was not mandatory for the diagnosis of placental abruption during the present analysis. Fetal arterial blood was obtained from the site of delivery, and UmA pH was measured immediately after delivery. Fetal acidosis was stratified by UmA pH <7.20, <7.10, or <7.00 based on a previous study, which reported that the UmA pH threshold of 7.20 was associated with an increased risk of adverse short-term outcomes,14 UmA pH threshold of 7.10 was associated with an increased risk of adverse neurological sequelae,15 and cerebral palsy was more frequent at UmA pH <7.00.16