International standards for early fetal size and pregnancy dating based on ultrasound measurement of crown–rump length in the first trimester of pregnancy

Authors

A. T. Papageorghiou, University of Oxford
S. H. Kennedy, University of Oxford
L. J. Salomon, Universit´e Paris Descartes
E. O. Ohuma, University of Oxford
L. Cheikh Ismail, University of Oxford
F. C. Barros, Universidade Católica de Pelotas
A. Lambert, University of Oxford
Maria Carvalho, Aga Khan UniversityFollow
Y. A. Jaffer, Ministry of Health, Muscat
E. Bertino, Università degli Studi di Torino
M. G. Gravett, University of Washington - Seattle Campus
D. G. Altman, University of Oxford
M. Purwar, Ketkar Hospital
J. A. Noble, University of Oxford
R. Pang, Peking University
C. G. Victora, Universidade Federal de Pelotas
Z. A. Bhutta, Aga Khan UniversityFollow
J. Villar, University of Oxford

Document Type

Article

Department

Obstetrics and Gynaecology (East Africa)

Abstract

Objectives: There are no international standards for relating fetal crown–rump length (CRL) to gestational age (GA), and most existing charts have considerable methodological limitations. The INTERGROWTH-21^st Project aimed to produce the first international standards for early fetal size and ultrasound dating of pregnancy based on CRL measurement.

Methods: Urban areas in eight geographically diverse countries that met strict eligibility criteria were selected for the prospective, population-based recruitment, between 9 + 0 and 13 + 6 weeks' gestation, of healthy well-nourished women with singleton pregnancies at low risk of fetal growth impairment. GA was calculated on the basis of a certain last menstrual period, regular menstrual cycle and lack of hormonal medication or breastfeeding in the preceding 2 months. CRL was measured using strict protocols and quality-control measures. All women were followed up throughout pregnancy until delivery and hospital discharge. Cases of neonatal and fetal death, severe pregnancy complications and congenital abnormalities were excluded from the study.

Results: A total of 4607 women were enrolled in the Fetal Growth Longitudinal Study, one of the three main components of the INTERGROWTH-21^st Project, of whom 4321 had a live singleton birth in the absence of severe maternal conditions or congenital abnormalities detected by ultrasound or at birth. The CRL was measured in 56 women at < 9 + 0 weeks' gestation; these were excluded, resulting in 4265 women who contributed data to the final analysis. The mean CRL and SD increased with GA almost linearly, and their relationship to GA is given by the following two equations (in which GA is in days and CRL in mm): mean CRL = −50.6562 + (0.815118 × GA) + (0.00535302 × GA²); and SD of CRL = −2.21626 + (0.0984894 × GA). GA estimation is carried out according to the two equations: GA = 40.9041 + (3.21585 × CRL^0.5) + (0.348956 × CRL); and SD of GA = 2.39102 + (0.0193474 × CRL).

Conclusions: We have produced international prescriptive standards for early fetal linear size and ultrasound dating of pregnancy in the first trimester that can be used throughout the world. © 2014 Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Objectives: There are no international standards for relating fetal crown–rump length (CRL) to gestational age (GA), and most existing charts have considerable methodological limitations. The INTERGROWTH-21^st Project aimed to produce the first international standards for early fetal size and ultrasound dating of pregnancy based on CRL measurement.

Methods: Urban areas in eight geographically diverse countries that met strict eligibility criteria were selected for the prospective, population-based recruitment, between 9 + 0 and 13 + 6 weeks' gestation, of healthy well-nourished women with singleton pregnancies at low risk of fetal growth impairment. GA was calculated on the basis of a certain last menstrual period, regular menstrual cycle and lack of hormonal medication or breastfeeding in the preceding 2 months. CRL was measured using strict protocols and quality-control measures. All women were followed up throughout pregnancy until delivery and hospital discharge. Cases of neonatal and fetal death, severe pregnancy complications and congenital abnormalities were excluded from the study.

Results: A total of 4607 women were enrolled in the Fetal Growth Longitudinal Study, one of the three main components of the INTERGROWTH-21^st Project, of whom 4321 had a live singleton birth in the absence of severe maternal conditions or congenital abnormalities detected by ultrasound or at birth. The CRL was measured in 56 women at < 9 + 0 weeks' gestation; these were excluded, resulting in 4265 women who contributed data to the final analysis. The mean CRL and SD increased with GA almost linearly, and their relationship to GA is given by the following two equations (in which GA is in days and CRL in mm): mean CRL = −50.6562 + (0.815118 × GA) + (0.00535302 × GA²); and SD of CRL = −2.21626 + (0.0984894 × GA). GA estimation is carried out according to the two equations: GA = 40.9041 + (3.21585 × CRL^0.5) + (0.348956 × CRL); and SD of GA = 2.39102 + (0.0193474 × CRL).

Conclusions: We have produced international prescriptive standards for early fetal linear size and ultrasound dating of pregnancy in the first trimester that can be used throughout the world. © 2014 Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Publication (Name of Journal)

Ultrasound in Obstetrics and Gynecology

Recommended Citation

Papageorghiou, A. T., Kennedy, S. H., Salomon, L. J., Ohuma, E. O., Ismail, L. C., Barros, F. C., Lambert, A., Carvalho, M., Jaffer, Y. A., Bertino, E., Gravett, M. G., Altman, D. G., Purwar, M., Noble, J. A., Pang, R., Victora, C. G., Bhutta, Z. A., Villar, J. (2014). International standards for early fetal size and pregnancy dating based on ultrasound measurement of crown–rump length in the first trimester of pregnancy. Ultrasound in Obstetrics and Gynecology, 44(6), 641-648.
Available at: https://ecommons.aku.edu/eastafrica_fhs_mc_obstet_gynaecol/32