Background
Delivery of a macrosomic fetus can be linked with significant maternal and perinatal morbidity. Detection of the macrosomic fetus prior to delivery could have a significant impact on reducing that morbidity.

Aims
The purpose of this study was to determine the likelihood of detection of macrosomia at the time of labour and delivery admission using ultrasound.

Methods
Retrospective review using the electronic medical record and delivery room logs to identify women admitted to labour and delivery with a birthweight of ≥4000 g.

Results
There were 272 macrosomic neonates delivered between January 2010 and December 2012, of which, 91 (33.46%) were identified as macrosomic by ultrasound. Using Spearman correlation, the association between the estimated fetal weight by ultrasound and birthweight was r = 0.214 (95% CI: 0.098–0.325; P = 0.0004). In bivariate analyses, only White race was significant for macrosomia detection with 59 of 149 (39.6%) identified compared with 32 of 123 (26.02%) (P = 0.020) non‐White people. In the multivariate model, race remained significant. The odds of being labelled macrosomia for White people was 2.051 (95% CI: 1.188–3.542) compared with non‐White people (P = 0.010).

Conclusions
Only 33% of fetuses whose birthweight was ≥4000 g were identified by a labour and delivery ultrasound. White race was the only significant factor that increased the odds of having a correct diagnosis of macrosomia by ultrasound.