TABLE 4.

Prediction of spontaneous preterm birth (<37 weeks of gestation) by customized CL percentile and CL

Gestational age at measurement	Screening method	Sensitivity	Specificity	+LR	−LR	PPV	NNE
20–23 6/7	CL<15 mm	0.24 (0.20–0.28)	0.99 (0.98–0.99)	17.40 (12.70–23.80)	0.77 (0.73–0.81)	0.70 (0.63–0.77)	1.40
	CL<25 mm	0.35 (0.31–0.40)	0.95 (0.94–0.96)	7.20 (60–8.70)	0.68 (0.64–0.73)	0.50 (0.44–0.55)	2.00
	Customized CL of <10th percentile	0.45 (0.41–0.50)	0.93 (0.93–0.94)	6.90 (5.90–8.10)	0.59 (0.54–0.64)	0.49 (0.44–0.53)	2.00
24–27 6/7	CL<15 mm	0.20 (0.16–0.24)	0.98 (0.97–0.98)	8.50 (6.50–11.10)	0.82 (0.79–0.86)	0.53 (0.4–0.6)	1.90
	CL<25 mm	0.36 (0.31–0.40)	0.92 (0.91–0.93)	4.60 (3.90–5.40)	0.70 (0.65–0.75)	0.38 (0.33–0.42)	2.60
	Customized CL of <10th percentile	0.46 (0.42–0.51)	0.93 (0.92–0.93)	6.20 (5.30–7.20)	0.58 (0.54–0.63)	0.45 (0.41–0.49)	2.20
28–31 6/7	CL<15 mm	0.21 (0.17–0.25)	0.97 (0.96–0.97)	6.80 (5.30–8.70)	0.81 (0.78–0.85)	0.45 (0.38–0.52)	2.20
	CL<25 mm	0.42 (0.37–0.46)	0.89 (0.88–0.90)	3.70 (3.20–4.30)	0.66 (0.61–0.71)	0.31 (0.27–0.35)	3.20
	Customized CL of <10th percentile	0.45 (0.41–0.50)	0.94 (0.94–0.95)	8.00 (6.80–9.40)	0.58 (0.53–0.63)	0.49 (0.44–0.54)	2.00
32–35 6/7	CL<15 mm	0.19 (0.15–0.24)	0.96 (0.95–0.96)	4.50 (3.40–6.00)	0.84 (0.80–0.89)	0.27 (0.21–0.33)	3.70
	CL<25 mm	0.45 (0.39–0.51)	0.84 (0.82–0.85)	2.70 (2.40–3.20)	0.66 (0.59–0.73)	0.18 (0.15–0.21)	5.60
	Customized CL of <10th percentile	0.39 (0.33–0.44)	0.95 (0.95–0.96)	8.50 (6.90–10.40)	0.64 (0.59–0.70)	0.41 (0.35–0.47)	2.40

CL, cervical length; −LR, negative likelihood ratio; +LR, positive likelihood ratio; NNE, number needed to evaluate (1/PPV); PPV, positive predictive value.