Sonographic fetal weight estimation in normal and overweight/obese healthy term pregnant women by gestation-adjusted projection (GAP) method

• Published in: Archives of gynecology and obstetrics Vol. 293; no. 4; pp. 775 - 781
• Main Authors: Paganelli, Simone, Soncini, Emanuele, Comitini, Giuseppina, Palomba, Stefano, La Sala, Giovanni Battista
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-04-2016; Springer Nature B.V
• Subjects: Accuracy; Adult; Anthropometry; Biometry; Birth Weight; Body Mass Index; Cohort Studies; Endocrinology; Female; Fetal Weight; Gynecology; Human Genetics; Humans; Infant, Low Birth Weight - physiology; Infant, Newborn; Maternal-Fetal Medicine; Medicine; Medicine & Public Health; Obesity; Obstetrics/Perinatology/Midwifery; Overweight; Predictive Value of Tests; Pregnancy; Pregnant Women; Regression Analysis; Term Birth; Ultrasonic imaging; Ultrasonography, Prenatal - methods; Ultrasonography, Prenatal - standards; Obesity; Sonographicfetal weight estimation; Ultrasound fetal weight; Estimated fetal weight accuracy; Ultrasound estimated fetal weight; Fetal weight formulas; Hadlockfetal weight
• ISSN: 0932-0067; 1432-0711
• DOI: 10.1007/s00404-015-3910-z

Purpose
The objective of this study is to assess the ultrasound accuracy in fetal weight estimation related to the time distance between the actual weight recorded at delivery and the period of sonography among normal and overweight/obese pregnant women within 3 weeks prior birth at term.
Methods
Four-hundred and ninety patients with healthy pregnancy were studied in a cohort study. The absolute percent error in estimation was achieved by gestation-adjusted projection method from Hadlock model for weight calculation as measure of accuracy. The mean percentage error variation over the weeks was correlated to maternal body mass index (BMI, Kg/m
2
) at ultrasound. The relationship between BMI and ultrasound performance was assessed by linear regression.
Results
The overall proportion of supposed sonographic estimated fetal weight at birth within ±10 % of the birth weight significantly declines over the weeks (
P
 = .016). The trend toward a progressive deterioration in ultrasound accuracy is not statistically significant for normal weight women (
P
 = .272) but it is for over-weight/obese (
P
 = .044). On univariate analysis, the absolute percent error and absolute error are positively related to BMI.
Conclusions
Accuracy is related to the week at ultrasound scan with a gradual deterioration over the time and it worsens with increasing distance in days between the date of ultrasounds and delivery. The deterioration is greater for BMI ≥ 25.