Table 1.

Studies reporting the use of progesterone as an adjunct to cerclage.

Study	Design	Sample size	Documented average cervical length (mm)	Mean gestational age (weeks) cerclage	Cerclage type	Progesterone type	Total duration of progesterone therapy (weeks)	Gestational age (weeks) delivery	Outcome	Overall rate of PTB
Sherman 1966, [2]	Observational cohort*	33/540	n/a	Variable	Both	17-αOHPC IM	Variable to 36	39.3	LB	n/a
Vitoratos et al., 1996 [3]	Prospective cohort	8/18	n/a	14-15	Shirodkar	OHP IM†	Preoperative one dose	>37	PTB < 37 wga	6% (<37)††
Zakut and Lanciano, 1981 [4]	Retrospective cohort	30/60	14 ± 4.5	14.6 ± 2.83	Both	17-αOHPC IM	15	n/a	PTB < 24 wga hospitalization BW Apgar score	13.3% (<24)
Berghella et al., 2010 [5]	Retrospective cohort	47/148	19.0	18.9	McDonald	17-αOHPC IM	From 16 to 36	Not reported	PTB < 37 wga PTB < 35 wga PTB < 32 wga PTB < 28 wga PTB < 24 wga PM	49% (<37) 30% (<35) 17% (<32) 9% (<28) 4% (<24)
Rafael et al., 2011 [6]	Retrospective cohort	15/58	18 (12–22)	21 (16–22)	n/a	17-αOHPC IM	From 16–20 to 36	35 (27-28)	PTB < 35 wga PTB < 32 wga PTB < 28 wga BW	40% (<35) 33.3% (<32) 33.3% (<28)
Rebarber et al., 2008 [7]	Retrospective cohort	232/1882	n/a	n/a	n/a	17-αOHPC IM	13.5 ± 5	35.4 ± 4.7	PTB < 37 wga PTB < 35 wga PTB < 32 wga	40.5% (<37) 25.9% (<32) 13.4% (<32)

n/a: not available, 17-αOHPC: 17-alpha-hydroxyprogesterone acetate, IM: intramuscular, wga: weeks gestational age, PTB: preterm birth, LB: live birth, BW: birth weight, and PM: perinatal death (stillbirth or postnatal death prior to hospital discharge).

*Unable to specify based on the review of an article whether the observational study was prospective or retrospective in nature.

^†This agent was reported as hydroxyprogesterone hexanoate.

^††Did not specify whether PTB was in progesterone plus cerclage treatment group.