How accurate is fetal biometry in the assessment of fetal age?
OBJECTIVE
The purpose of the study was to assess the accuracy of fetal biometry in the midtrimester of pregnancy in the assignment of fetal age.


METHODS
A total of 152 singleton, 67 twin, and 19 triplet gestations resulting from in vitro fertilization with ultrasonographic fetal biometry from 14 to 22 weeks made up the study population. A gestational age prediction equation was derived from singletons with the use of stepwise linear regression. This equation was compared with 38 previously published equations and then applied to the twin and triplet populations.


RESULTS
Head circumference was the best predictor of gestational age (random error [SD] 3.77 days). Addition of abdominal circumference and femur length to head circumference improved the accuracy of the dating equation (random error 3.35 days). Most dating formulas had systematic errors of <1 week. The systematic error was -0.32 day for averaging the singleton-based predictions for twins and -1.26 days for triplets.


CONCLUSIONS
Gestational age assessment with the use of fetal biometry from 14 to 22 weeks is accurate for singleton, twin, and triplet gestations.
Chervenak
F A
FA
Department of Obstetrics and Gynecology, The New York Hospital-Cornell Medical Center, New York 10021, USA.
Skupski
D W
DW
Romero
R
R
Myers
M K
MK
Smith-Levitin
M
M
Rosenwaks
Z
Z
Thaler
H T
HT
D000005:Abdomen / Q000000981:diagnostic imaging; D001699:Biometry; D002508:Cephalometry; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000196:embryology; D005307:Fertilization in Vitro; D005333:Fetus / Q000033:anatomy & histology*; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D012044:Regression Analysis; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014310:Triplets; D014427:Twins; D016216:Ultrasonography, Prenatal