Estimation of Fetal Weight by Measuring Abdominal Circumference, Abdominal Subcutaneous Soft Tissue Thickness, Femur Length and Mid-thigh Soft Tissue Thickness

Estimation of Fetal Weight by Measuring Abdominal Circumference, Abdominal Subcutaneous Soft Tissue Thickness, Femur Length and Mid-thigh Soft Tissue Thickness: Cross Sectional Study.

Traditional methods for estimating fetal weight (EFW) often miss the mark because they focus on bone and circumference while ignoring fetal fat. This study proposes a more inclusive formula to fix that. Current models (using BPD, HC, AC, and FL) are the standard but suffer from high observer variability. These formulas struggle at the extremes (macrosomia or growth restriction) and fail to account for fetal adiposity, which makes up 10-12% of a newborn's mass. The study introduces a novel formula that moves beyond simple bone measurements by integrating Soft Tissue Thickness (STT). By accounting for a broader range of biological variants and fat distribution, this new model aims to provide a non-inferior, more precise predictive value for fetal weight compared to traditional methods.

Study Overview

• Status: Not yet recruiting
• Conditions: Fetal Macrosomia; Intrauterine Growth Restriction (IUGR); Intrauterine Growth Disorders (IUGR and Macrosomia)
• Intervention / Treatment: Other: 3rd trimester ultrasound examination within 48-72 hours of delivery

Detailed Description

Accurate estimation of fetal weight (EFW) is fundamental to modern obstetric management. Traditional sonographic biometry-utilizing biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL)-is the standard for predictive modeling. However, these parameters are limited by significant inter- and intra-observer variability and a loss of precision at the extremes of fetal weight, such as in cases of macrosomia or growth restriction. Furthermore, conventional formulas often fail to account for fetal adiposity, which constitutes 10-12% of total neonatal body mass. Recent literature suggests that the integration of soft tissue thickness (STT) measurements-specifically mid-arm, subscapular, abdominal subcutaneous, and mid-thigh thickness-can enhance the accuracy of EFW. While the Scioscia and modified Scioscia formulas rely exclusively on FL and mid-thigh measurements, this study proposes a novel, multi-parametric approach. By combining AC, fetal abdominal subcutaneous tissue thickness, FL, and mid-thigh soft tissue thickness, we hypothesize that our formula offers a non-inferior predictive value. This model accounts for a broader range of biological variants and soft tissue distribution patterns that significantly influence overall fetal mass.

Detailed history (maternal age, obstetric history, medical history, previous macrosomic fetuses, previous shoulder dystocia). Gestational age is calculated from the first day of the last menstrual period and confirmed by either a first- or second-trimester ultrasound scan. When the ultrasound-determined gestational age differed from that calculated from the last menstrual period by >7 days in the first trimester, or by >10 days in the second trimester, the ultrasound-determined gestational age is used.

The study will be bi-phasic, 1st phase is model development phase in which we develop a mathematical model for fetal weight estimation incorporating (abdominal circumference, fetal abdominal subcutaneous soft tissue thickness, femur length, mid-thigh soft tissue thickness), the 2nd phase is a validation and comparison phase in which we test our model and compare it to modified Scioscia formula and conventional Hadlock formula.

For measurement of femur length (FL) Each caliper is placed at the ends of the ossified diaphysis without including the distal femoral epiphysis if it is visible.

For the measurement of AC, the transverse section of the fetal abdomen should be as circular as possible, and the fetal spine preferably in the 3- or 9-o'clock position, umbilical vein at the level of the portal sinus, stomach visible and kidneys not visible. The AC is measured directly at the outer surface of the skin line, with ellipse calipers.

Mid-thigh STT: measured linearly in the standard longitudinal section used for FL measurement. In the middle third of the fetal thigh, with the femur lying parallel to the transducer, mid-thigh STT was measured from the outer margin of the skin to the outer margin of the femur shaft. The measurement was taken, providing that the greater and the lesser trochanter are turned upwards. This section assures the correct view of the lateral side of the femur (vastus lateralis, which is the biggest part of the quadriceps femoris) Abdominal Subcutaneous STT: Measured at the level of the AC plane, anterior 1/3rd of abdominal circumference between outer and inner edges of abdominal wall by ultrasound.

Actual birth weight (AFW) was immediately measured after delivery by a neonatologist using digital medical neonatal scale.

• Study Type: Observational
• Enrollment (Estimated): 300

Contacts and Locations

• Study Contact: Name: Khaled Mustafa Attyia, Master's degree; Phone Number: +201005503250; Email: khaled.hussien@med.aun.edu.eg

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

full term pregnant women within 48-72 hours before delivery

Description

Inclusion Criteria:

1. Singleton Gestation.
2. Gestational Age: Participants must be at a term ≥ 37 weeks
3. Timing of Examination: Sonographic EFW must be performed within 48 -72 hours prior to delivery.
4. Welling to share in the study.

Exclusion Criteria:

1. Fetal Anomalies.
2. Amniotic Fluid Disorders: oligohydramnios or polyhydramnios
3. Maternal morbid obesity (BMI > 40 kg/m2)
4. Maternal medical disorders: as diabetes, hypertension, systemic lupus erythromatosis or others affecting fetal growth
5. Fetal Hydrops
6. Fetal Malpresentation
7. Fetal growth restriction

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Full term pregnant women; full term pregnant women with in 48-72 hours of delivery either cesarean section, spontaneous vaginal delivery or induced vaginal delivery.	Other: 3rd trimester ultrasound examination within 48-72 hours of delivery; ultrasound examination of full-term pregnant women with 48-72 hours of delivery measuring Abdominal circumference, fetal abdominal subcutaneous soft tissue thickness, femur length and mid-thigh soft tissue thickness.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
development and validation of novel method for fetal weight estimation	a novel module for fetal weight estimation depending on abdominal circumference, fetal abdominal subcutaneous soft tissue thickness, femur length, mid-thigh soft tissue thickness.	within 48- 72 hours of delivery

Collaborators and Investigators

• Sponsor: Assiut University

Publications and helpful links

General Publications

• Paydary K, Seraj SM, Zadeh MZ, Emamzadehfard S, Shamchi SP, Gholami S, Werner TJ, Alavi A. The Evolving Role of FDG-PET/CT in the Diagnosis, Staging, and Treatment of Breast Cancer. Mol Imaging Biol. 2019 Feb;21(1):1-10. doi: 10.1007/s11307-018-1181-3.
• Deter RL. Individualized growth assessment: evaluation of growth using each fetus as its own control. Semin Perinatol. 2004 Feb;28(1):23-32. doi: 10.1053/j.semperi.2003.10.011.
• Scioscia M, Scioscia F, Vimercati A, Caradonna F, Nardelli C, Pinto LR, Selvaggi LE. Estimation of fetal weight by measurement of fetal thigh soft-tissue thickness in the late third trimester. Ultrasound Obstet Gynecol. 2008 Mar;31(3):314-20. doi: 10.1002/uog.5253.
• Lee W, Deter RL, McNie B, Goncalves LF, Espinoza J, Chaiworapongsa T, Romero R. Individualized growth assessment of fetal soft tissue using fractional thigh volume. Ultrasound Obstet Gynecol. 2004 Dec;24(7):766-74. doi: 10.1002/uog.1779.
• Lee W, Deter RL, McNie B, Goncalves LF, Espinoza J, Chaiworapongsa T, Balasubramaniam M, Romero R. The fetal arm: individualized growth assessment in normal pregnancies. J Ultrasound Med. 2005 Jun;24(6):817-28.
• Larciprete G, Di Pierro G, Barbati G, Deaibess T, Jarvis S, Valensise H, Romanini ME, Gioia S, Arduini D. Could birthweight prediction models be improved by adding fetal subcutaneous tissue thickness? J Obstet Gynaecol Res. 2008 Feb;34(1):18-26. doi: 10.1111/j.1447-0756.2007.00741.x.
• Bernstein IM, Goran MI, Amini SB, Catalano PM. Differential growth of fetal tissues during the second half of pregnancy. Am J Obstet Gynecol. 1997 Jan;176(1 Pt 1):28-32. doi: 10.1016/s0002-9378(97)80006-3.
• Galan HL, Rigano S, Radaelli T, Cetin I, Bozzo M, Chyu J, Hobbins JC, Ferrazzi E. Reduction of subcutaneous mass, but not lean mass, in normal fetuses in Denver, Colorado. Am J Obstet Gynecol. 2001 Oct;185(4):839-44. doi: 10.1067/mob.2001.117350.
• Skovron ML, Berkowitz GS, Lapinski RH, Kim JM, Chitkara U. Evaluation of early third-trimester ultrasound screening for intrauterine growth retardation. J Ultrasound Med. 1991 Mar;10(3):153-9. doi: 10.7863/jum.1991.10.3.153.
• Chang TC, Robson SC, Boys RJ, Spencer JA. Prediction of the small for gestational age infant: which ultrasonic measurement is best? Obstet Gynecol. 1992 Dec;80(6):1030-8.
• Kurmanavicius J, Burkhardt T, Wisser J, Huch R. Ultrasonographic fetal weight estimation: accuracy of formulas and accuracy of examiners by birth weight from 500 to 5000 g. J Perinat Med. 2004;32(2):155-61. doi: 10.1515/JPM.2004.028.
• Dudley NJ. A systematic review of the ultrasound estimation of fetal weight. Ultrasound Obstet Gynecol. 2005 Jan;25(1):80-9. doi: 10.1002/uog.1751.
• Rosati P, Exacoustos C, Caruso A, Mancuso S. Ultrasound diagnosis of fetal macrosomia. Ultrasound Obstet Gynecol. 1992 Jan 1;2(1):23-9. doi: 10.1046/j.1469-0705.1992.02010023.x.

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): December 30, 2027
• Study Completion (Estimated): July 30, 2028

Study Registration Dates

• First Submitted: May 4, 2026
• First Submitted That Met QC Criteria: May 4, 2026
• First Posted (Actual): May 8, 2026

Study Record Updates

• Last Update Posted (Actual): May 12, 2026
• Last Update Submitted That Met QC Criteria: May 7, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: fetal growth restriction; Macrosomia; fetal weight estimation; fetal soft tissue thickness; mid-thigh soft tissue thickness; fetal abdominal soft tissue thickness
• Additional Relevant MeSH Terms: Urogenital Diseases; Endocrine System Diseases; Pathologic Processes; Female Urogenital Diseases and Pregnancy Complications; Body Weight; Pregnancy Complications; Diabetes Mellitus; Fetal Diseases; Growth Disorders; Diabetes Complications; Diabetes, Gestational; Pregnancy in Diabetics; Birth Weight; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Fetal Growth Retardation; Fetal Macrosomia; Pregnancy; Reproduction; Reproductive Physiological Phenomena; Reproductive and Urinary Physiological Phenomena; Parturition
• Other Study ID Numbers: AssiutFetalWT

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No