TABLE 5.

Prediction of sPTB by customized CL percentile and CL based on measurements at 20 to 23 6/7 weeks of gestation

Gestational age at spontaneous preterm delivery	Screening method	+LR	−LR
<37 wk	CL<25	7.20 (6.00–8.70)	0.68 (0.64–0.73)
	Customized CL of <pth percentile (P=2.0)	12.30 (9.80–15.50)	0.68 (0.64–0.73)
	Customized CL of <10th percentile	6.90 (5.90–8.10)	0.59 (0.54–0.64)
<36 wk	CL<25	7.20 (6.20–8.30)	0.56 (0.52–0.61)
	Customized CL of <pth percentile (P=1.8)	13.20 (10.90–16.00)	0.58 (0.54–0.62)
	Customized CL of <10th percentile	6.80 (6.00–7.70)	0.47 (0.43–0.52)
<35 wk	CL<25	7.00 (6.00–8.10)	0.54 (0.49–0.59)
	Customized CL <pth percentile(P=1.8)	12.10 (10.10–14.50)	0.55 (0.51–0.61)
	Customized CL of <10th percentile	6.60 (5.80–7.40)	0.45 (0.40–0.50)
<34 wk	CL<25	7.50 (6.60–8.70)	0.49 (0.44–0.55)
	Customized CL of <pth percentile (P=1.9)	12.50 (10.50–14.80)	0.50 (0.45–0.55)
	Customized CL of <10th percentile	6.80 (6.00–7.60)	0.41 (0.36–0.46)
<33 wk	CL<25	7.80 (6.80–8.90)	0.44 (0.39–0.50)
	Customized CL of <pth percentile (P=2.0)	12.50 (10.60–14.70)	0.45 (0.39–0.51)
	Customized CL of <10th percentile	6.90 (6.20–7.80)	0.36 (0.31–0.42)

pth percentile was set to match the −LR for the 25 mm cutoff.

CL, cervical length; −LR, negative likelihood ratio; +LR, positive likelihood ratio.