title: Does Time of Delivery Influence the Risk of Neonatal Morbidity?
abstract: OBJECTIVE
  To examine whether time of delivery influences the risk of neonatal morbidity among women with singleton pregnancies.
  
  
  METHODS
  Secondary analysis of data from the Maternal Fetal Medicine Units Network Factor V Leiden Mutation study. We categorized time of delivery as day (07:00-16:59), evening (17:00-23:59), and overnight (midnight-06:59). Severe neonatal morbidity was defined by at least one of the following: respiratory distress syndrome, transient tachypnea of the newborn, sepsis, seizures, neonatal intensive care admission, or a 5-minute APGAR ≤3. We calculated frequencies of severe neonatal morbidity by time of delivery. Multivariate analysis was performed to determine whether time of delivery was independently associated with severe neonatal morbidity.
  
  
  RESULTS
  Among 4,087 women, 1,917 (46.9%) delivered during the day, 1,140 (27.9%) delivered in the evening, and 1,030 (25.2%) delivered overnight. We observed no significant differences in the rates of neonatal morbidity between delivery time periods (day: 12.3%; evening: 12.8%; overnight: 12.6%; p = 0.9). No significant association was observed between time of delivery and neonatal morbidity after adjustment for maternal, obstetric, and peripartum factors.
  
  
  CONCLUSIONS
  Our findings suggest that time of delivery is not associated with severe neonatal morbidity.
authors.affiliation: Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California.
authors.forename: Kathleen F
authors.initials: KF
authors.lastname: Brookfield
authors.affiliation: Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California.
authors.forename: Katharine
authors.initials: K
authors.lastname: O'Malley
authors.affiliation: Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California.
authors.forename: Yasser Y
authors.initials: YY
authors.lastname: El-Sayed
authors.affiliation: Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, California.
authors.forename: Yair J
authors.initials: YJ
authors.lastname: Blumenfeld
authors.affiliation: Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, California.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Butwick
mesh_terms: D000328:Adult; D039602:After-Hours Care / Q000706:statistics & numerical data*; D001034:Apgar Score; D002585:Cesarean Section / Q000706:statistics & numerical data; D015331:Cohort Studies; D036861:Delivery, Obstetric / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal / Q000706:statistics & numerical data; D007751:Labor, Induced / Q000706:statistics & numerical data; D008297:Male; D000071074:Neonatal Sepsis / Q000453:epidemiology*; D011247:Pregnancy; D012127:Respiratory Distress Syndrome, Newborn / Q000453:epidemiology*; D012640:Seizures / Q000453:epidemiology*; D013997:Time Factors; D059245:Transient Tachypnea of the Newborn / Q000453:epidemiology*; D055815:Young Adult