Table 2 Agreement in gestational age estimated by last menstrual period (LMP) and Farr examination compared to ultrasound

Median GA (days)

(Interquartile range)

273.9 (268.2, 279.3)

276.0^a (268.0, 282.0)

286.7^a (286.7, 288.6)

Mean difference (days) (95% CI)

Reference

1.4 (0.7, 2.0)

12.9 (12.2, 13.5)

Intra-class correlation coefficient (95% CI)

Reference

0.78 (0.74, 0.80)

0.26 (0.15, 0.37)

Concordance correlation coefficient (95% CI)

Reference

0.63 (0.59, 0.67)

0.05 (0.04, 0.07)

 ±7 days

Reference

625 (68.5)

166 (24.2)

 ±10 days

Reference

731 (80.2)

254 (37.1)

 ±14 days

Reference

806 (88.4)

382 (55.8)