Charts of fetal size: 4. Femur length

Abstract

Objective To construct a new size chart for fetal femur length. Design A prospective, cross sectional study of fetuses scanned once only for the purpose of the study at gestations between 12 and 42 weeks. Setting The routine ultrasound department of a London teaching hospital. Subject The fetuses of 663 women seen in the routine antenatal booking clinic whose ultrasound and menstrual dates agreed within 10 days. Results Femur length was measured on 649 of the 663 fetuses. A linear‐cubic regression model was fitted to estimate the mean and a separate linear regression to estimate the standard deviation. Gentiles were derived by combining these two regression models, assuming that the measurements have a normal distribution at each gestational age. A new chart for femur size is presented and compared with previously published data. Conclusions We have constructed a new size chart for fetal femur length taking into consideration the increasing variability with increasing gestational age. We have compared our chart with other published data, and believe that the differences seen may be largely due to methodological differences.

Impaired uteroplacental blood flow in pregnancies complicated by falciparum malaria

“…Ultrasound-derived gestational age assessment was used when menstrual dates were unknown (n = 310, 31%) or when measurement of fetal size fell more than 2 SD above or below the mean for gestation calculated from menstrual history (n = 220, 22%). Gestational age was calculated from the charts of Chitty et al 15,16 .…”

Fetal Size in a Rural Melanesian Population with Minimal Risk Factors for Growth Restriction: An Observational Ultrasound Study from Papua New Guinea

“…[7][8][9]29 For this analysis, we selected a cross-sectional sample (one measurement per fetus) from the overall number of sonographic measurements taken in the participant population. Samples were selected such that the number of observations was maximally dispersed over gestation to enable the best possible distribution of values for statistical analysis.…”

“…3,4 The International Fetal and Newborn Growth Consortium (INTERGROWTH)-21 study assesses fetal growth in cohorts with no obvious risk factors for fetal growth restriction (FGR) in eight geographical areas, including Kenya and India, with the aim of developing global standards for optimal fetal growth. 5 The most commonly used ultrasound-estimated fetal weight (EFW), birth weight (BW), and size reference charts (nomograms) are derived from industrialized and largely Caucasian populations, [6][7][8][9] and they may not be appropriate in all populations 1 ; particularly, their ability to accurately detect FGR may be limited. 10 A definitive diagnosis of FGR is made when serial ultrasound scans show a persistent downward deviation from the expected growth trajectory.…”

Fetal Skeletal System

“…[5][6][7][8][9] The measurement of the femur length (FL) is a part of standard 2nd and 3rd trimester biometry. Since the long bones are invariably affected in the severe skeletal dysplasias, this measurement provides the first clue that bone formation or growth is abnormal.…”