Ultrasound Fetal Femur Length in Normal Pregnant Northern Thai Women

Abstract

The measurement of fetal femur length (FL) in each week of pregnancy between the 14th and the 40th week was carried out at Maharaj Nakorn Chiang Mai Hospital form April 1989 to December 1990. A total of 1208 measurements were obtained from 435 patients, 203 patients had one measurement each and 1005 measurements were obtained from the remaining 232 patients. Growth of FL in the Thai populaion showed an asymptotic curve like that of Europeans or Americans but our values were significantly lower. The linear quadratic function was an accu rate model describing the relation between femur length and menstrual age. Mean, standard deviation, 5'h, 50'h and 95th percentiles were calculated and predicted. FL for each menstrual week was also demonstrated. From the serial measurements performed, we found that the growth rate of the femur begins at 3.0 mm/week and slowly decreases to 1.3 mm/week toward 40 weeks of gestation. (Thai J Obstet Gynaecol 1991;3:79-83.)