Do early pregnancy ultrasound measurements correlate with fetal nuchal translucency at 11-14 weeks?

OBJECTIVE To assess whether extremes in nuchal translucency (NT) thickness measurements at 11-14 weeks of gestation are preceded by departures from normal in early ultrasound biometry or embryonic heart rate in euploid fetuses. METHODS This was a retrospective analysis of data from women with singleton pregnancies examined in early pregnancy between June 2002 and January 2003, who subsequently had a nuchal translucency (NT) scan. The early pregnancy scan was performed transvaginally, and the crown-rump length (CRL), mean gestational sac diameter (GS), mean yolk sac diameter (YS) and embryonic heart rate (HR) were measured where possible. At the second scan CRL and NT were measured. RESULTS A total of 534 singleton pregnancies were included in the analysis. The mean maternal age was 30 (range, 14-45) years, and 59.4% of the patients were nulliparous. The mean CRL was 11.5 (range, 1.4-30.0) mm at the first scan and 62.8 (range, 42.0-88.0) mm at the second scan. GS, YS and HR measurements were obtained in 87.6%, 72.5% and 72.5% of cases, respectively. No statistically significant correlation was observed between NT and Z-scores of early pregnancy: GS (r = 0.013, P = 0.77), YS (r = 0.039, P = 0.44) or HR (r = 0.016, P = 0.76). GS, YS and HR were not significantly different in fetuses with NT measurements below the 10th percentile or above the 90th percentile (P = 0.24, 0.84 and 0.60, respectively). CONCLUSION Ultrasound biometry and heart rate measured in early pregnancy are not related to nuchal translucency measurements at 11-14 weeks of gestation in chromosomally normal fetuses.