title: Paper gestational age wheels are generally inaccurate.
abstract: OBJECTIVE
  To compare the estimated date of confinement of paper gestational wheels to the estimated date of confinement of APPs wheels using a standard last menstrual period.
  
  
  METHODS
  Obstetric providers were asked for their gestational wheels. The last menstrual period was set at Jan. 1, 2013, and the estimated date of confinement obtained was compared with the estimated date of confinement of Oct. 8th if the pregnancy completed 280 days. The process was performed on 20 electronic APPs downloadable to cell phones. The process was repeated for both for the leap year of 2012.
  
  
  RESULTS
  Thirty-one paper wheels from a variety of sources were collected. Ten wheels (35%) were consistent with the standard pregnancy duration of 280 days. Among the wheels surveyed, the largest discrepancy was 4 days short of 280 days. Two wheels gave an estimated date of confinement that differed from each other by 7 days. Wheels from the same source did not agree with each other. Twenty electronic gestational age calculators were examined. All 20 gave an estimated date of confinement of Oct. 8 consistent with 280 days. None of the paper gestational wheels but all of the APPs corrected for a leap year.
  
  
  CONCLUSIONS
  In contrast to APPs gestational age calculators, the estimated date of confinement of the majority of paper wheels deviated from the standard pregnancy duration of 280 days. Precision in gestational age assessment is critical in a variety of clinical settings and heightened by the focus by payers and reporting agencies on elective deliveries before 39 weeks. The use of paper gestational age wheels should be abandoned.
authors.affiliation: Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, St. Joseph's Hospital and Medical Center, and the Department of Obstetrics and Gynecology, Creighton University School of Medicine, Phoenix, AZ.
authors.forename: Linda R
authors.initials: LR
authors.lastname: Chambliss
authors.affiliation: Hospital Corporation of America, Nashville, TN.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Clark
mesh_terms: D001699:Biometry / Q000295:instrumentation* / Q000379:methods; D005260:Female; D005865:Gestational Age; D006801:Humans; D008597:Menstrual Cycle; D011247:Pregnancy
keywords: accuracy of gestational wheels