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.