Gestational Age & EDD Estimation Methods
Methods of Prediction/Estimation of GA & EDD
There a 2 fetal biometry prediction/estimation methods used to predict/estimate either GA or EDD, but not both GA & EDD using the same method. If a method predicts/estimates GA it must calculate EDD from GA using the equivalent of Naegele's rule; and, conversely, if a method predicts/estimates EDD it must calculate GA from EDD using the equivalent of Naegele's rule, but in reverse. However, establishing GA for a pregnancy from the estimated end of a pregnancy (i.e., EDD) is problematic. Predicting/estimating GA and predicting/estimating EDD are 2 very different things and should never be presented as if both methods are predicting/estimating the same thing. They are not. This was made explicitly clear by Dr. David J. R. Hutchon who developed the Hutchon Method of Population-based Direct EDD Estimation (PDEE), Hutchon 1998.
Norway's NCFM eSnurra Group claim to predict/estimate both EDD and GA by conflating prediction/estimation with calculation. It is important to understand a prediction/estimation of EDD is not synonymous with the calculation of GA using the equivalent of Naegele's rule, but in reverse. This is important to understand in order to avoid unnecessary confusion and deception. There is already enough conflate-to-obfuscate in the political sphere lest it be allowed to further obfuscate the practice of evidence-based medicine with respect to obstetric and fetal medicine.
Comprehensive Resource:
There a 2 fetal biometry prediction/estimation methods used to predict/estimate either GA or EDD, but not both GA & EDD using the same method. If a method predicts/estimates GA it must calculate EDD from GA using the equivalent of Naegele's rule; and, conversely, if a method predicts/estimates EDD it must calculate GA from EDD using the equivalent of Naegele's rule, but in reverse. However, establishing GA for a pregnancy from the estimated end of a pregnancy (i.e., EDD) is problematic. Predicting/estimating GA and predicting/estimating EDD are 2 very different things and should never be presented as if both methods are predicting/estimating the same thing. They are not. This was made explicitly clear by Dr. David J. R. Hutchon who developed the Hutchon Method of Population-based Direct EDD Estimation (PDEE), Hutchon 1998.
Norway's NCFM eSnurra Group claim to predict/estimate both EDD and GA by conflating prediction/estimation with calculation. It is important to understand a prediction/estimation of EDD is not synonymous with the calculation of GA using the equivalent of Naegele's rule, but in reverse. This is important to understand in order to avoid unnecessary confusion and deception. There is already enough conflate-to-obfuscate in the political sphere lest it be allowed to further obfuscate the practice of evidence-based medicine with respect to obstetric and fetal medicine.
- Predict/Estimate Gestational Age
Origin: Dr. Stuart Campbell, London, U.K., Campbell (1969)
Method: Campbell Method of Estimation of Gestational Age
Publication: The prediction of fetal maturity by ultrasonic measurement of the biparietal diameter
Prediction/Estimation: Gestational age (GA) in days on the date of the ultrasound exam
Compliment Calculation: EDD can be calculated using the equivalent of Naegele's rule by subtracting the predicted/estimated GA from the date of the ultrasound to calculate a virtual LMPD to which, depending on the method, 280, 281, 282, or 283 days are added to calculate EDD.
Norwegian Implementation: Bergen Group's Terminhjulet or Term wheel - Predict/Estimate Date of Delivery (EDD)
Origin: Dr. David J. R. Hutchon, Darlington, U.K., Hutchon (1998)
Method: Hutchon Method of Population-based Direct EDD Estimation (PDEE)
Publication: 'Back to the Future' for Hermanni Boerhaave or 'A rational way to generate ultrasound scan charts for estimating the date of delivery'
Prediction/Estimation: Number of days remaining from the date of the ultrasound exam to birth/delivery (or interval to delivery (ITD))
Compliment Calculation (warning: this is problematic): NCFM eSnurra Group calculate GA using the equivalent of Naegele's rule, but in reverse, by subtracting (depending on the method) 280, 281, 282, or 283 days days from the EDD date to calculate a virtual LMPD (GA = 0w+0). Or, GA can be calculated using the equivalent of Naegele's rule, but in reverse, by subtracting the predicted/estimated number of days remaining on the ultrasound date to birth/delivery from 282 days to calculate GA on the date of the ultrasound exam. [Note: Dr. Hutchon warned against calculating GA in this way by explicitly stating: "Provided the fetus can be assessed as normal using other criteria [i.e., direct GA estimation in conjunction with all available evidence in the practice of evidence-based medicine], this chart can be used to provide the best estimate of the date of delivery (EDD)." and "...there is no pretence that this method is determining fetal age" (Hutchon 1998).
Norwegian Implementation: NCFM eSnurra Group (Trondheim Group)'s NCFM eSnurra or eSnurra "method" is an appropriated, plagiarized, misused implementation of the Hutchon Method of PDEE. NCFM eSnurra Group uses the Hutchon Method of PDEE to estimate EDD, but NCFM eSnurra Group also claim to estimate GA. NCFM eSnurra Group's "method" does not estimate GA; NCFM eSnurra Group must calculate GA using the equivalent of Naegele's rule, in reverse. The fact NCFM eSnurra Group also obviate a woman's key pregnancy dates within a government-mandated protocol of evidence-obviated medicine in order to eliminate a woman's medical evidence is an additional, dangerous, separate issue. Unfortunately, but not surprisingly, when these issues are combined, the consequences include unnecessary, increased medical risks, critical medical mistakes and grievous medical harms.
Comprehensive Resource:
- UpToDate Literature Review: "Prenatal assessment of gestational age, date of delivery, and fetal weight"(Source: "Prenatal assessment of gestational age, date of delivery, and fetal weight" Andrew P MacKenzie, MDCourtney D Stephenson, DOEdmund F Funai, MD. Section Editor:Deborah Levine, MD; Deputy Editor:Vanessa A Barss, MD, FACOG. UpToDate. Literature review current through: Apr 2019. | This topic last updated: Jul 12, 2018. Topic 5391 Version 41.0)
Prediction/Estimation Methods
1998: Hutchon Method of Population-based Direct EDD Estimation (PDEE) (Darlington, United Kingdom): used first-trimester and second-trimester ultrasound measurements of fetal crown-rump length (CRL) and biparietal diameter (BPD), respectively, to estimate the mean remaining gestation time to term or date of delivery. The supporting models used least-squares and polynomial regressions in a retrospective, epidemiological, population-sample-based study of 298 routine first-trimester and 79 second-trimester ultrasound fetal measurements whereby all data were collected prospectively by tracking individual pregnancies from their ultrasound exam dates to their actual delivery dates; no otherwise historical ultrasound data were collected or used. Each fetus was entered in the statistics with a single measurement from first-trimester and second-trimester measurements. Gestational age at expected term (EDD) was 280 days. Optimal number of subjects: as many as possible. Comparability & reproduciblilty for other researches: Excellent, all techniques & functions were directly implemented in the major statistical packages. Resulting paper: "'Back to the Future' for Hermanni Boerhaave or 'A rational way to generate ultrasound scan charts for estimating the date of delivery'", Hutchon DJR, ObGyn Ultrasound, ObGyn.net 19.07.1998: http://www.obgyn.net/obgyn-ultrasound/back-future-hermanni-boerhaave-or-rational-way-generate-ultrasound-scan-charts-estimating-date) For date authentication and provenance purposes see Internet Archive WayBackMahine link to the 22.02.1999 archive of Dr. Hutchon's seminal 1998 paper, the first date it was archived. https://web-beta.archive.org/web/19990222085509/http://www.obgyn.net:80/us/cotm/9807/cotm_9807.htm Also, following is an Internet Archive WayBackMahine link to the 10.10.2004 archive of Dr. Hutchon's website, the first date it was archived by Internet Archive WayBackMahine: https://web-beta.archive.org/web/20041010152259/hutchon.net Note: A separate, unpublished study by Dr. Hutchon included more than 500 ultrasound scans of biparietal diameter (BPD), head circumference (HC) and crown-rump length (CRL) and produced charts that correlated well with conventional charts. However, even with over 500 observations in his models' datasets, Dr. Hutchon did not think the results definitive enough to be used for more than proving and demonstrating the Hutchon Method of Population-based Direct EDD Estimation (PDEE) to a large research group or institute with the funding to help him take his original idea and method to the next level for implementation (Source: BMFMS, Feb. 1998, Poster Presentations: Pregnancy Outcome, "97. Customized ultrasound dating charts" p. S57)
2001: Taipale & Hiilesmaa Collaboration with National Center for Fetal Medicine (NCFM), Trondheim University Hospital Trondheim, Norway and Helsinki University Central Hospital, Helsinki, Finland): appropriated, plagiarized and used the Hutchon Method of Population-based Direct EDD Estimation (PDEE) with an approach that used first-trimester, singleton pregnancies, ultrasound measurements of fetal crown rump length (CRL), biparietal diameter (BPD), and femur length (FL) to predict/estimate the remaining gestation days from ultrasound exam date to delivery date. The supporting models used univariate & multiple linear regression (GA was limited to >= 37w) and non-linear models in a retrospective, population-based, study of 17,221 routine ultrasound exams acquired from historical database records. Each fetus in the study was restricted to a single measurement in the statistics. Optimal number of subjects: as many as possible. Comparability & reproduciblilty for other researches: Excellent, all techniques & functions were implemented in the major statistical packages. Resulting paper: Predicting Delivery Date by Ultrasound and Last Menstrual Period in Early Gestation TAIPALE, PEKKA MD, PhD; HIILESMAA, VILHO MD, PhD. Obstetrics & Gynecology: February 2001 - Volume 97 - Issue 2 - p 189–194. Received May 30, 2000. Received in revised form September 25, 2000. Accepted October 12, 2000.
2006: Bergen Group Method or Terminhjulet or Term wheel (Bergen, Norway): based on 2 studies to establish GA assessment charts for head circumference (HC) and biparietal diameter (BPD) (Johnsen et al. 2004) and femur length (FL) (Johnsen et al. 2005). Both studies used a single measurement from each fetus to establish charts for prediction/estimation of GA by ultrasound for weeks 10-23. The supporting models used fractional polynomial regressions in 2 prospective, cross-sectional, sample-based studies of 650 normal, singleton pregnancies with reliable, regular menstrual cycles of 28 days ± 3 days, with each fetus in each study entered with a single measurement in the statistics. Gestational age at expected date of delivery was 282 days. Optimal number of subjects: never greater than number defined by the statistical power calculation. Comparability & reproduciblilty for other researches: Excellent, all techniques and functions were directly implemented in the major statistical packages. Resulting papers: 1) Fetal age assessment based on ultrasound head biometry and the effect of maternal and fetal factors. Johnsen SL1, Rasmussen S, Sollien R, Kiserud T., Acta, Obstet Gynecol Scand. 2004 Aug;83(8):716-23. and 2) Fetal age assessment based on femur length at 10–25 weeks of gestation, and reference ranges for femur length to head circumference ratios, Synnøve Lian Johnsen, Svein Rasmussen, Rita Sollien, Torvid Kiserud, Acta Obstet Gynecol Scand. 2005 Aug;84(8):725-33. [Note: both of these studies were subsequently embedded in a third study (Johnsen et al. 2006), a longitudinal study on growth of fetal biometric measurements: Longitudinal reference charts for growth of the fetal head, abdomen and femur. Synnøve Lian Johnsen, Tom Wilsgaard, Svein Rasmussen, Rita Sollien, Torvid Kiserud. European Journal of Obstetrics & Gynecology and Reproductive Biology 127 (2006) 172–185.]
2007: NCFM eSnurra Group or Trondheim Group eSnurra Method (Trondheim, Norway): appropriated, plagiarized and used the Hutchon Method of Population-based Direct EDD Estimation (PDEE) with an approach that used second-trimester, singleton pregnancy, ultrasound measurements of biparietal diameter (BPD) and femur length (FL) to estimate the median remaining gestation days from ultrasound exam date to delivery date. The supporting models used local linear quantile regression in a retrospective, epidemiological, population-based study of 41,343 routine ultrasound exams acquired from historical database records. Each fetus in the study was not restricted to a single measurement in the statistics. Gestational age at expected date of delivery was 283 days. Optimal number of subjects: as many as possible. Comparability & reproduciblilty for other researches: Poor, all techniques & functions were not directly implemented in the major statistical packages; used a custom implementation of statistical techniques not available to other researchers. Resulting paper: A direct method for ultrasound Prediction of day of delivery: a new, population-based approach, H. K. Gjessing, P. Grøttum, S. H. Eik-Nes, Ultrasound Obstet Gynecol 2007; 30: 19–27
2010: Salomon et al Group Method (Paris, France): appropriated, plagiarized and used the Hutchon Method of Population-based Direct EDD Estimation (PDEE) with an approach that used first-trimester, singleton pregnancies, ultrasound measurements of fetal crown rump length (CRL), biparietal diameter (BPD), head circumference (HC), and abdominal circumference (AC) to estimate the median remaining gestation days from ultrasound exam date to delivery date. The supporting models used spline-smoothed quantile regression in a prospective, population-based, study of 3,738 routine ultrasound exams. Each fetus in the study was restricted to a single measurement in the statistics. Gestational age at expected date of delivery was 282 days. Optimal number of subjects: as many as possible. Comparability & reproduciblilty for other researches: Excellent, all techniques & functions were implemented in the major statistical packages. Resulting paper: Prediction of the date of delivery based on first trimester ultrasound measurements: An independent method from estimated date of conception, Laurent J. Salomon, Costanza Pizzi, Antonio Gasparrini, Jean-Pierre Bernard & Yves Ville, The Journal of Maternal-Fetal & Neonatal Medicine Volume 23, 2010 - Issue 1.
2001: Taipale & Hiilesmaa Collaboration with National Center for Fetal Medicine (NCFM), Trondheim University Hospital Trondheim, Norway and Helsinki University Central Hospital, Helsinki, Finland): appropriated, plagiarized and used the Hutchon Method of Population-based Direct EDD Estimation (PDEE) with an approach that used first-trimester, singleton pregnancies, ultrasound measurements of fetal crown rump length (CRL), biparietal diameter (BPD), and femur length (FL) to predict/estimate the remaining gestation days from ultrasound exam date to delivery date. The supporting models used univariate & multiple linear regression (GA was limited to >= 37w) and non-linear models in a retrospective, population-based, study of 17,221 routine ultrasound exams acquired from historical database records. Each fetus in the study was restricted to a single measurement in the statistics. Optimal number of subjects: as many as possible. Comparability & reproduciblilty for other researches: Excellent, all techniques & functions were implemented in the major statistical packages. Resulting paper: Predicting Delivery Date by Ultrasound and Last Menstrual Period in Early Gestation TAIPALE, PEKKA MD, PhD; HIILESMAA, VILHO MD, PhD. Obstetrics & Gynecology: February 2001 - Volume 97 - Issue 2 - p 189–194. Received May 30, 2000. Received in revised form September 25, 2000. Accepted October 12, 2000.
2006: Bergen Group Method or Terminhjulet or Term wheel (Bergen, Norway): based on 2 studies to establish GA assessment charts for head circumference (HC) and biparietal diameter (BPD) (Johnsen et al. 2004) and femur length (FL) (Johnsen et al. 2005). Both studies used a single measurement from each fetus to establish charts for prediction/estimation of GA by ultrasound for weeks 10-23. The supporting models used fractional polynomial regressions in 2 prospective, cross-sectional, sample-based studies of 650 normal, singleton pregnancies with reliable, regular menstrual cycles of 28 days ± 3 days, with each fetus in each study entered with a single measurement in the statistics. Gestational age at expected date of delivery was 282 days. Optimal number of subjects: never greater than number defined by the statistical power calculation. Comparability & reproduciblilty for other researches: Excellent, all techniques and functions were directly implemented in the major statistical packages. Resulting papers: 1) Fetal age assessment based on ultrasound head biometry and the effect of maternal and fetal factors. Johnsen SL1, Rasmussen S, Sollien R, Kiserud T., Acta, Obstet Gynecol Scand. 2004 Aug;83(8):716-23. and 2) Fetal age assessment based on femur length at 10–25 weeks of gestation, and reference ranges for femur length to head circumference ratios, Synnøve Lian Johnsen, Svein Rasmussen, Rita Sollien, Torvid Kiserud, Acta Obstet Gynecol Scand. 2005 Aug;84(8):725-33. [Note: both of these studies were subsequently embedded in a third study (Johnsen et al. 2006), a longitudinal study on growth of fetal biometric measurements: Longitudinal reference charts for growth of the fetal head, abdomen and femur. Synnøve Lian Johnsen, Tom Wilsgaard, Svein Rasmussen, Rita Sollien, Torvid Kiserud. European Journal of Obstetrics & Gynecology and Reproductive Biology 127 (2006) 172–185.]
2007: NCFM eSnurra Group or Trondheim Group eSnurra Method (Trondheim, Norway): appropriated, plagiarized and used the Hutchon Method of Population-based Direct EDD Estimation (PDEE) with an approach that used second-trimester, singleton pregnancy, ultrasound measurements of biparietal diameter (BPD) and femur length (FL) to estimate the median remaining gestation days from ultrasound exam date to delivery date. The supporting models used local linear quantile regression in a retrospective, epidemiological, population-based study of 41,343 routine ultrasound exams acquired from historical database records. Each fetus in the study was not restricted to a single measurement in the statistics. Gestational age at expected date of delivery was 283 days. Optimal number of subjects: as many as possible. Comparability & reproduciblilty for other researches: Poor, all techniques & functions were not directly implemented in the major statistical packages; used a custom implementation of statistical techniques not available to other researchers. Resulting paper: A direct method for ultrasound Prediction of day of delivery: a new, population-based approach, H. K. Gjessing, P. Grøttum, S. H. Eik-Nes, Ultrasound Obstet Gynecol 2007; 30: 19–27
2010: Salomon et al Group Method (Paris, France): appropriated, plagiarized and used the Hutchon Method of Population-based Direct EDD Estimation (PDEE) with an approach that used first-trimester, singleton pregnancies, ultrasound measurements of fetal crown rump length (CRL), biparietal diameter (BPD), head circumference (HC), and abdominal circumference (AC) to estimate the median remaining gestation days from ultrasound exam date to delivery date. The supporting models used spline-smoothed quantile regression in a prospective, population-based, study of 3,738 routine ultrasound exams. Each fetus in the study was restricted to a single measurement in the statistics. Gestational age at expected date of delivery was 282 days. Optimal number of subjects: as many as possible. Comparability & reproduciblilty for other researches: Excellent, all techniques & functions were implemented in the major statistical packages. Resulting paper: Prediction of the date of delivery based on first trimester ultrasound measurements: An independent method from estimated date of conception, Laurent J. Salomon, Costanza Pizzi, Antonio Gasparrini, Jean-Pierre Bernard & Yves Ville, The Journal of Maternal-Fetal & Neonatal Medicine Volume 23, 2010 - Issue 1.
"the comparative evaluation of the two methods really amounts to comparing apples to pears."
