Table 1.

Strategies for prevention of spontaneous preterm delivery (sPTD) in asymptomatic women with a singleton pregnancy, based on sonographic cervical length (CL) screening and vaginal progesterone treatment

Strategy	Population screened	Population not screened	Definition of short cervix		Treatment
			CL measurement at 18 + 0 to 20 + 6 weeks	CL measurement at 21 + 0 to 23 + 6 weeks
No screening	NA	All women	NA	NA	No standardized treatment
No screening, treat high‐risk group	NA	All women	NA	NA	Women with previous sPTD or late miscarriage are treated with vaginal progesterone without screening
Universal screening	All women	NA	≤ 25 mm (base‐case); ≤ 29 mm; ≤ 20 mm	≤ 25 mm (base‐case); ≤ 27 mm; ≤ 20 mm	Screened women with a short cervix are treated with vaginal progesterone
High‐risk‐based screening	Women with previous PTD, previous late miscarriage or cervical conization	All women except those with previous PTD, previous late miscarriage or cervical conization	NA	≤ 25 mm (base‐case); ≤ 27 mm; ≤ 20 mm	Screened women (previous PTD, late miscarriage or cervical conization) with a short cervix are treated with vaginal progesterone
Low‐risk‐based screening	All women except those with previous sPTD or previous late miscarriage	Women with previous sPTD or previous late miscarriage	≤ 25 mm (base‐case); ≤ 29 mm; ≤ 20 mm	≤ 25 mm (base‐case); ≤ 27 mm; ≤ 20 mm	Screened women with a short cervix are treated with vaginal progesterone; not‐screened women with a previous sPTD or late miscarriage are treated with vaginal progesterone
Nullipara screening	All nulliparous women (except those with a previous late miscarriage)	All women except screened nulliparous women	≤ 25 mm (base‐case); ≤ 29 mm; ≤ 20 mm	≤ 25 mm (base‐case); ≤ 27 mm; ≤ 20 mm	Screened women with a short cervix are treated with vaginal progesterone; not‐screened women with a previous sPTD or late miscarriage are treated with vaginal progesterone

NA, not applicable.