1368: Gestational Age Prediction by Femur Length in Bangladesh

Abstract

Fetal femur length is an important parameter for determining gestational age. If we use tables based on our own population, gestational age estimation will be more accurate. This study was therefore designed to determine the gestational age by fetal femur length measurement in our country. Healthy gravid patients with optimal dates were included in a prospective study. Fetal femur length along with other parameters was measured. A table and a graph were prepared by Polynomial regression model. Previously established nomograms were compared with it. The gestational age estimated from the femur length measurements of 1223 healthy gravid momen, from 13 to 40 weeks are presented here in a tabulated form. 3rd. 10th, 50th, 90th and 97th Percentiles, mean and standard deviations were also derived. The quadratic model showed a good fit to the data when superimposed on the scater diagram. It gave 95% confidence interval. Also model was fitted seperately to standard deviations as a function of gestational age. There was a gradual increase of the femur length measurements up to 37th week. From 13 to 27 weeks gestation, there was no clinically important difference between this and western nomograms for predicting gestational age but after 32 weeks the difference with western nomograms became significant. This nomogram is unique for Bangladeshi population. It will give more accurate gestational age assessment than the western tables that are still followed in our country, especially in the 3rd trimester.