title: How Accurate Is the Dating of Scheduled 39-Week Deliveries?
abstract: OBJECTIVE
  We assessed the impact of a policy preventing scheduled repeat cesarean deliveries at less than 39 weeks, accounting for potential inaccuracies in pregnancy dating.
  
  
  METHODS
  We analyzed a cohort of repeat cesarean deliveries before and after the policy change and used chi-square testing to compare the proportion of deliveries at less than 39 weeks. We assessed whether the reduction in early-term deliveries was different if the gestational age was based on the documented estimated date of delivery (EDD) as compared with best obstetric dating.
  
  
  RESULTS
  Our cohort consisted of 213 women; 112 before the policy change and 101 after. Using the EDD assigned at delivery, there was a 12.1% absolute decrease in scheduled deliveries at less than 39 weeks (25.0-12.9%; p = 0.025). However, using the EDD by best obstetric dating, there was no significant change (32.1-25.7%; p = 0.305). Of the 85 discrepant EDDs, providers were more likely to assign an earlier EDD (63.5%; p = 0.013).
  
  
  CONCLUSIONS
  Our institution's policy change led to a 12.1% absolute reduction in documented, scheduled early-term deliveries, however only a 6.4% absolute decline using best obstetric dating. Policy initiatives to reduce early-term deliveries should consider the source and accuracy of the assigned pregnancy dating.
authors.affiliation: Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Stephanie H
authors.initials: SH
authors.lastname: Guseh
authors.affiliation: Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Little
authors.affiliation: Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Chloe A
authors.initials: CA
authors.lastname: Zera
authors.affiliation: Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Julian N
authors.initials: JN
authors.lastname: Robinson
mesh_terms: D000328:Adult; D001071:Appointments and Schedules; D002585:Cesarean Section / Q000706:statistics & numerical data*; D036861:Delivery, Obstetric / Q000706:statistics & numerical data*; D005260:Female; D005865:Gestational Age; D006291:Health Policy; D006801:Humans; D008404:Massachusetts; D016134:Organizational Policy; D011247:Pregnancy; D011295:Prenatal Care; D012189:Retrospective Studies; D062606:Tertiary Care Centers; D019564:Unnecessary Procedures / Q000706:statistics & numerical data*