Third trimester ultrasound for the prediction of the large for gestational age fetus in low-risk population and evaluation of contingency strategies.
OBJECTIVE
Evaluation of the effectiveness of third trimester fetal biometry and Doppler studies in predicting the birth of a large for gestational age neonate (LGA ≥ 95(th) centile). Assessment of the value of integrated models (combining maternal characteristics, first trimester parameters, third trimester fetal biometry) and the usefulness of contingency strategies.


METHODS
Observational cross-sectional study on 2308 uncomplicated singleton pregnancies examined at 11 to 14 weeks and at 30 to 34 weeks.


RESULTS
Ultrasound estimated fetal weight (EFW, area under the curve (AUC) = 0.83) was the best single predictor of LGA. Maternal weight, delta nuchal translucency and EFW were independent predictors for the integrated model, but the latter was not statistically better (AUC = 0.84) than using EFW alone. The detection rates for LGA were 72.5% and 73.7% for a 25% screen positive rate, by EFW and the third trimester integrated model respectively. A contingency strategy of rescanning 50% of the population in the third trimester according to the risk estimation by a first trimester prediction model results in detection rate of 64.7% for LGA for the same 25% screen positive rate (AUC = 0.78).


CONCLUSIONS
Third trimester ultrasound is an effective screening modality for identifying fetal macrosomia. A contingency strategy utilizing first trimester parameters can reduce the need for unnecessary examinations.
Fetal Medicine Unit, 3rd Department of Obstetrics and Gynaecology, University of Athens, Attikon University Hospital, Athens, Greece.
Athanasios
A
Pilalis
Athena P
AP
Souka
Ioannis
I
Papastefanou
Vasiliki
V
Michalitsi
Perikles
P
Panagopoulos
Charalambos
C
Chrelias
Dimitrios
D
Kassanos
D000293:Adolescent; D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D005320:Fetal Macrosomia / Q000175:diagnosis / Q000000981:diagnostic imaging*; D020567:Fetal Weight / Q000502:physiology; D005333:Fetus / Q000033:anatomy & histology / Q000502:physiology; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000209:etiology; D008875:Middle Aged; D007744:Obstetric Labor Complications / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000209:etiology; D011153:Population; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000209:etiology; D011263:Pregnancy Trimester, Third / Q000502:physiology; D011379:Prognosis; D012306:Risk; D016216:Ultrasonography, Prenatal / Q000379:methods; D055815:Young Adult