Femur length in normal fetuses and the correlation between crown-rump length and gestational age at 11–14 weeks in a Chinese Han population: a preliminary study

Abstract

Femur length in normal fetuses and the correlation between crown-rump length and gestational age at 11–14 weeks in a Chinese Han population: a preliminary study J. Wang 1 , T. Jiang 1 , X. Zhu 1 , G. Tian 2 1Department of Ultrasound Medicine, the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 2State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou (China) Summary Objective: To establish normative data for the distribution of fetal femur length (FL) with increasing crown-rump length (CRL) and gestational age (GA) at 11–14 weeks, and to construct equations of fetal FL among normal fetuses in a Chinese Han population. Materials and Methods: The present retrospective review study included singleton fetuses assessed by ultrasonography between 11 and 14 weeks gestation from March 2015 to May 2016 at the First Affiliated Hospital (College of Medicine of Zhejiang University). The FL and CRL were measured and recorded. The regression models were fitted to estimate the mean at each GA or CRL. Results: There were 414 fetuses included. The equations generated to predict the FL from the GA or CRL had a high goodness-of-fit. The regression equations were described as follows: FL=0.479*GA^2-9.15*GA+47.018 and FL=0.001*CRL^2+0.032*CRL+0.424. Conclusion: The equations generated can be used to predict FL in a Chinese Han population and can be useful to detect fetal skeletal dysplasia, as well as early growth restriction, but additional clinical data is needed. Key words: Femur length; First trimester; Crown-rump length; Gestational age; Chinese pregnant women; Ultrasound.