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Table 3 Crown-rump length (CRL) measurements in relation to gestational age for the original equation fit reported by Verburg compared to model fit of the simulated data (Approach 2)

From: Estimation of gestational age in early pregnancy from crown-rump length when gestational age range is truncated: the case study of the INTERGROWTH-21stProject

  Verburg’s original equation Approach 2  
Estimated GA (weeks) Estimated GA (weeks) Difference (days)
CRL (mm) 3rdcentile Median 97thcentile 3rdcentile Median 97thcentiles 3rdcentile Median 97thcentile
10 6.88 7.50 8.18 7.08 7.71 8.39 -1.41 -1.45 -1.48
15 7.63 8.31 9.06 7.70 8.38 9.12 -0.52 -0.47 -0.41
20 8.22 8.96 9.77 8.25 8.98 9.77 -0.21 -0.12 -0.02
25 8.73 9.52 10.38 8.75 9.52 10.36 -0.11 0.00 0.12
30 9.19 10.02 10.92 9.20 10.01 10.90 -0.09 0.02 0.15
35 9.60 10.47 11.41 9.62 10.47 11.39 -0.11 0.01 0.14
40 9.99 10.89 11.87 10.01 10.89 11.86 -0.13 -0.01 0.13
45 10.36 11.29 12.31 10.38 11.29 12.29 -0.14 -0.02 0.12
50 10.70 11.67 12.72 10.72 11.67 12.70 -0.13 0.00 0.15
55 11.04 12.03 13.12 11.05 12.03 13.09 -0.09 0.04 0.20
60 11.36 12.39 13.50 11.37 12.37 13.46 -0.03 0.11 0.28
65 11.67 12.73 13.87 11.67 12.70 13.82 0.06 0.21 0.39
70 11.98 13.06 14.24 11.96 13.01 14.16 0.18 0.35 0.54
75 12.28 13.39 14.59 12.23 13.31 14.49 0.33 0.51 0.73
80 12.57 13.71 14.94 12.50 13.60 14.81 0.50 0.71 0.95
85 12.86 14.02 15.28 12.76 13.89 15.11 0.71 0.94 1.20
90 13.15 14.33 15.62 13.01 14.16 15.41 0.95 1.20 1.49
95 13.43 14.64 15.96 13.25 14.42 15.70 1.22 1.50 1.81
100 13.71 14.94 16.29 13.49 14.68 15.98 1.51 1.82 2.17