title: New charts for ultrasound dating of pregnancy and assessment of fetal growth: longitudinal data from a population-based cohort study.
abstract: OBJECTIVE
  Correct assessment of gestational age and fetal growth is essential for optimal obstetric management. The objectives of this study were, first, to develop charts for ultrasound dating of pregnancy based on crown-rump length and biparietal diameter and, second, to derive reference curves for normal fetal growth based on biparietal diameter, head circumference, transverse cerebellar diameter, abdominal circumference and femur length from 10 weeks of gestational age onwards.
  
  
  METHODS
  A total of 8313 pregnant women were included for analysis in this population-based prospective cohort study. All women had repeated ultrasound assessments to examine fetal growth.
  
  
  RESULTS
  Charts for ultrasound dating of pregnancy, based on crown-rump length and biparietal diameter, were derived. Internal validation with the actual date of delivery showed that ultrasound imaging provided reliable gestational age estimates. Up to 92% of deliveries took place within 37-42 weeks of gestation if gestational age was derived from ultrasound data, compared with 87% based on a reliable last menstrual period. The earlier the ultrasound assessment the more accurate the prediction of date of delivery. After 24 weeks of gestation a reliable last menstrual period provided better estimates of gestational age. Reference curves for normal fetal growth from 10 weeks of gestational age onwards were derived.
  
  
  CONCLUSIONS
  Charts for ultrasound dating of pregnancy and reference curves for fetal biometry are presented. The results indicate that, up to 24 weeks of pregnancy, dating by ultrasound examination provides a better prediction of the date of delivery than does last menstrual period. The earlier the ultrasound assessment in pregnancy, preferably between 10 and 12 weeks, the better the estimate of gestational age.
authors.affiliation: The Generation R Study Group, Erasmus Medical Center, Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands.
authors.forename: B O
authors.initials: BO
authors.lastname: Verburg
authors.forename: E A P
authors.initials: EA
authors.lastname: Steegers
authors.forename: M
authors.initials: M
authors.lastname: De Ridder
authors.forename: R J M
authors.initials: RJ
authors.lastname: Snijders
authors.forename: E
authors.initials: E
authors.lastname: Smith
authors.forename: A
authors.initials: A
authors.lastname: Hofman
authors.forename: H A
authors.initials: HA
authors.lastname: Moll
authors.forename: V W V
authors.initials: VW
authors.lastname: Jaddoe
authors.forename: J C M
authors.initials: JC
authors.lastname: Witteman
mesh_terms: D000005:Abdomen / Q000000981:diagnostic imaging / Q000196:embryology; D000328:Adult; D002531:Cerebellum / Q000000981:diagnostic imaging / Q000196:embryology; D018568:Crown-Rump Length; D005260:Female; D047109:Fetal Development; D005333:Fetus / Q000033:anatomy & histology; D005865:Gestational Age; D006257:Head / Q000000981:diagnostic imaging / Q000196:embryology; D006801:Humans; D008137:Longitudinal Studies; D011247:Pregnancy; D011446:Prospective Studies; D012016:Reference Values; D016216:Ultrasonography, Prenatal / Q000379:methods*