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Objectives: Development of descriptive table of gestational age (GA) based on fetal crown rump length (CRL) in Vietnam. Methods: This study was conducted at the Center for Prenatal Diagnosis, National Hospital Obstetrics and Gynecology. Gestational age based on the first day of last menstrual period (LMP) ranges from 10 weeks to 14 weeks and 6 days. Pregnant women who are healthy, have regular menstrual periods, have not used hormonal drugs or assisted reproductive methods before. Have ultrasound measured the length of the crown-rump of the embryo based on the mandatory criteria. Data were analysed using SPSS 20.0 software. Results: 1008 singleton fetuses that met criteria, were predicted GA according to LMP. There were 1008 fetal crown rump length recorded. The mean CRL was 59.95 ± 6.79 (mm), the mean gestational age according to KCC was: 12.13 ± 0.75 (weeks). Gestational age was linearly correlated with fetal crown rump length according to the equation: CRL = 6.602+ GAx 4.398 and GA= 8.889 + CRLx 0.54. Conclusion: Gestational age can be calculated based on fetal crown rump length index by linear equation: GA = 8.889 + CRLx 0.54. The equations can be applied to calculate gestational age in ultrasound practice in Vietnam.
Crown rump length, last menstrual period, gestational age
 Ioannou C, Talbot K, Ohuma E et al., Systematic review of methodology used in ultrasound studies aimed at creating charts of fetal size, BJOG: An International Journal of Obstetrics & Gynaecology, 2012; 119(12): 1425-1439.
 Royston P, Altman DG, Regression Using Fractional Polynomials of Continuous Covariates: Parsimonious Parametric Modelling, Journal of the Royal Statistical Society. Series C (Applied Statistics), 1994; 43(3): 429-467.
 Miller J, Turan S, Baschat AA, Fetal growth restriction, Semin Perinatol, 2008; 32(4): 274-80.
 Altman DG, Ohuma EO, Statistical considerations for the development of prescriptive fetal and newborn growth standards in the INTERGROWTH-21st Project, Bjog, 2013; 120: 76.
 Villar J, Altman DG, Purwar M et al. , The objectives, design and implementation of the INTERGROWTH-21st Project, Bjog, 2013; 120 Suppl 2, 9-26, v.
 Wanyonyi SZ, Napolitano R, Ohuma EO et al. , Image-scoring system for crown-rump length measurement, Ultrasound Obstet Gynecol, 2014; 44(6): 649-54.
 Bellera CA, Hanley JA, A method is presented to plan the required sample size when estimating regression-based reference limits, J Clin Epidemiol., 2007; 60(6): 610-5.
 Papageorghiou AT, Kennedy SH, Salomon LJ et al., International standards for early fetal size and pregnancy dating based on ultrasound measurement of crown-rump length in the first trimester of pregnancy, Ultrasound Obstet Gynecol, 2014; 44(6): 641-8.