Fetal abdominal circumference measurements of 35 and 38 cm as predictors of macrosomia. A risk factor for shoulder dystocia.
OBJECTIVE
To determine if ultrasound measurements of fetal abdominal circumference (AC) can be used to predict macrosomic infants.


METHODS
Using a computer database, 1,996 women at > or = 36 weeks' gestation, delivering a singleton infant and having an ultrasound examination within one week of delivery were studied. Fetal AC was evaluated to determine if it was useful in predicting the birth of a macrosomic infant, > 4,000 or > 4,500 g.


RESULTS
AC predicted infants > 4,500 g better than those > 4,000 g. Almost all macrosomic infants > 4,500 g had an AC of > or = 35 cm (68/69, or 99%), but many nonmacrosomic infants were also in this group (683). AC of > or = 38 cm occurred in 99 infants, and 37 of the 69 (53.6%) weighing > 4,500 g were identified. Most infants (78%) with AC > or = 38 cm weighed > 4,000 g.


CONCLUSIONS
Fetal AC was very helpful in identifying potential macrosomic infants. If AC was < 35 cm, the risk of infant birth weights > 4,500 g was < 1%. If AC was > or = 38 cm, the risk was 37% (37/99), and > 50% of these infants were identified (37/69, or 53.6%).
Gilby
J R
JR
Department of Obstetrics and Gynecology, University of South Florida College of Medicine, 4 Columbia Drive, Tampa, FL 33606, USA.
Williams
M C
MC
Spellacy
W N
WN
D000005:Abdomen / Q000000981:diagnostic imaging*; D000886:Anthropometry / Q000379:methods; D001724:Birth Weight; D004420:Dystocia / Q000209:etiology*; D005260:Female; D005320:Fetal Macrosomia / Q000150:complications* / Q000000981:diagnostic imaging*; D006801:Humans; D007231:Infant, Newborn; D011247:Pregnancy; D012189:Retrospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012782:Shoulder; D016216:Ultrasonography, Prenatal / Q000379:methods / Q000592:standards*