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

ASUM2938*1.8 (1.7 to 1.9) 𝑃 < 0 . 0 0 0 1
Hadlock30520.87 (0.81 to 0.93) 𝑃 < 0 . 0 0 0 1
Daya3052−0.80 (−0.84 to −0.77) 𝑃 < 0 . 0 0 0 1
Verburg641*−1.80 (−2.0 to −1.6) 𝑃 < 0 . 0 0 0 1
Old ASUM2997*0.23 (0.20 to 0.27) 𝑃 < 0 . 0 0 0 1
Robinson1476*−0.16 (−0.27 to −0.05) 𝑃 = 0 . 0 0 4 7

*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.