Ultrasonographic prediction of fetal macrosomia. Association with cesarean delivery.
OBJECTIVE
To investigate whether the incorrect ultrasonographic prediction of macrosomia affects the cesarean delivery rate among nonmacrosomic neonates.


METHODS
For this retrospective, cohort study, comprehensive ultrasonographic records were reviewed at two centers. Patients with singleton, nonanomalous gestations whose ultrasonography predicted an estimated fetal weight > or = 4,000 g composed one cohort (n = 135), while the other cohort (n = 129) consisted of patients whose ultrasonography predicted an estimated fetal weight between 3,000 and 3,999 g. We compared the cesarean delivery rate in neonates falsely diagnosed with macrosomia (false positives) with the rate in those correctly diagnosed as nonmacrosomic (true negatives).


RESULTS
The rate of cesarean delivery was significantly higher among those falsely diagnosed by ultrasonography with a macrosomic fetus as compared to those with a fetus truly diagnosed as nonmacrosomic (42.3% vs. 24.3%, relative risk = 1.74, 95% confidence interval 1.09-2.78). Subgroup analyses excluding diabetic mothers and multiparous women and comparing false positives with true negatives with neonatal birth weights between 3,500 and 4,000 g (birth weights similar to false positives) demonstrated significantly increased cesarean delivery rates among false positives.


CONCLUSIONS
Even in nonmacrosomic neonates, the antenatal ultrasonographic diagnosis of suspected macrosomia is associated with a significant increase in cesarean delivery rates.
Parry
S
S
Department of Obstetrics and Gynecology, University of Pennsylvania Medical Center, Philadelphia 19104-4283, USA. sparry@obgyn.upenn.edu
Severs
C P
CP
Sehdev
H M
HM
Macones
G A
GA
White
L M
LM
Morgan
M A
MA
D000328:Adult; D001724:Birth Weight; D002585:Cesarean Section; D015331:Cohort Studies; D005189:False Positive Reactions; D005260:Female; D005320:Fetal Macrosomia / Q000000981:diagnostic imaging*; D020567:Fetal Weight; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal