Table 2. Efficacy of cervical pessary placement in preventing perinatal morbidity and mortality in women with a singleton pregnancy and a short cervix compared with control.

Secondary outcome	Trials	Pessary(Events/Total)	Control(Events/Total)	RR(95% CI)	P value	I2
preterm birth <34 wk	Goya15, Hui16, Nicolaides13	79/703	109/709	0.75 (0.23 to 2.39)	0.62	90%
preterm birth <30 wk	Hui16, Nicolaides13	38/513	31/519	1.24 (0.78 to 1.96)	0.36	0%
preterm birth <28 wk	Hui16, Nicolaides13	27/513	18/519	1.52 (0.84 to 2.74)	0.16	0%
respiratory distress syndrome	Goya15, Hui16, Nicolaides13	38/703	50/709	0.79 (0.22 to 2.90)	0.72	82%
necrotizing enterocolitis	Goya15, Nicolaides13	6/650	5/654	0.95 (0.11 to 8.13)	0.96	47%
intraventricular hemorrhage	Goya15, Hui16, Nicolaides13	28/703	28/709	1.04 (0.63 to 1.74)	0.87	0%
neonatal sepsis	Goya15, Hui16, Nicolaides13	33/703	37/709	0.67 (0.23 to 1.96)	0.46	69%
retinopathy of prematurity	Goya15, Nicolaides13	5/650	3/654	1.21 (0.05 to 28.10)	0.91	66%
fetal death	Goya15, Hui16, Nicolaides13	8/703	5/709	1.61 (0.53 to 4.90)	0.4	NA
neonatal death	Goya15, Hui16, Nicolaides13	8/703	6/709	1.32 (0.48 to 3.66)	0.59	0%
perinatal death	Goya15, Hui16, Nicolaides13	16/703	12/709	1.33 (0.65 to 2.76)	0.44	0%
birth weight <1500 g	Goya15, Nicolaides13	48/650	54/654	0.72 (0.18 to 2.84)	0.64	90%
birth weight <2500 g	Goya15, Nicolaides13	113/650	142/654	0.60 (0.16 to 2.17)	0.43	95%
premature preterm rupture of membranes	Goya15, Hui16	9/243	25/245	0.39 (0.09 to 1.71)	0.21	72%
corticosteroid treatment for fetal maturation	Goya15, Hui16	89/243	129/245	0.75 (0.47 to 1.18)	0.22	37%
admission to neonatal intensive care unit	Hui16, Nicolaides13	61/513	51/519	1.23 (0.88 to 1.71)	0.23	0%