Ultrasound Reference Chart Based on IVF Dates to Estimate Gestational Age at 6–9 weeks’ Gestation

Table 5

Mean differences in gestational ages derived from The Monash Chart compared to those predicted by the six existing reference charts.

	𝑛	Mean differences in days (95% CI)	Comparison with gestation determined using The Monash Chart
ASUM	2938^*	1.8 (1.7 to 1.9)	𝑃<0.0001
Hadlock	3052	0.87 (0.81 to 0.93)	𝑃<0.0001
Daya	3052	−0.80 (−0.84 to −0.77)	𝑃<0.0001
Verburg	641^*	−1.80 (−2.0 to −1.6)	𝑃<0.0001
Old ASUM	2997^*	0.23 (0.20 to 0.27)	𝑃<0.0001
Robinson	1476^*	−0.16 (−0.27 to −0.05)	𝑃=0.0047

^*n values are less than 3052 because exact dates were not given for a number of CRL lengths in these charts. Verburg et al. [9], for instance, only provide exact dates for CRL lengths at 5, 10, and 15 mm.