Table 2. Performance of models to provide continuous estimates of gestational age.

	2 months storage (n=60)			4 months storage (n=61)			6 months storage (n=65)			12 months storage (n=38)
	Fresh	Stored	∆	Fresh	Stored	∆	Fresh	Stored	∆	Fresh	Stored	∆
Model 1	1.42 wks		-	1.35 wks		-	1.11 wks		-	1.60 wks		-
Model 2	1.21 wks	1.20 wks	-0.00	1.04 wks	1.08 wks	+0.04	0.93 wks	1.16 wks	+0.24	1.39 wks	1.48 wks	+0.10
∆	-0.22	-0.22		-0.31	-0.27		-0.19	+0.05		-0.22	-0.12

Data are expressed as RMSE, root mean squared error (average absolute deviation of ultrasound-validated vs. model estimated gestational in weeks); ∆, Black=unchanged, Green=improvement in model accuracy, Red=attenuation in model accuracy