CL<38mm P 95%CI 95%CI I2 RR Exclude the literature name The p values were after the sensitivity analysis Publication bias Quality of evidence
ptb<34 0.004* 0.72 0.57,0.90 43% 2.9 - - - low
ptb<37 0.06 0.92 0.84,1.01 11% 1.85 - - - low
miscarriage 0.21 0.77 0.5,1.16 30% 1.26 - - - low
sptb<34 0.03* 0.77 0.61,0.97 61% 2.18 Nicolaided 2015 0.003* + Very low
sptb<37 0.34 0.93 0.80,1.08 0% 0.96 - - - low
SM 0.18 0.72 0.44,1.17 0% 1.34 - - - low
DW <0.00001* 0.37 0.26,0.48 83% 6.31 Norman2021 <0.00001* Very low
C 0.71 1.14 0.58,2.21 0% 0.37 - - - low
VI 0.26 1.36 0.8,2.33 38% 1.14 - - - low
VD <0.00001* 3.22 2.52,4.11 94% 9.37 Merced2019 <0.00001* + low
<34PPROM 0.56 1.25 0.59,2.64 66% 0.58 Goya2015 0.08 + Very low
PPROM 0.07 1.67 0.96,2.9 62% 1.82 Norman2021 0.69 + Very low
C-section 0.93 1.01 0.9,1.12 0% 0.09 - - - low
VB <0.00001* 1.56 1.32,1.83 93% 5.34 Norman2021 <0.00001 + Very low
intrauterine death or stillbirth 0.18 1.41 0.86,2.33 0% 1.36 - - - low
neonatal death 0.01* 0.50 0.29,0.87 73% 2.47 Leim2013 0.99 + Very low
<2500 0.00001 0.74 0.67,0.81 90% 6.02 Merced2019 0.003 + Very low
<1500 0.9 1.02 0.77,1.34 0% 0.13 - - - low
NE 0.0004* 0.33 0.18,0.61 0% 3.52 - - - low
IVH 0.5 0.79 0.41,1.55 41% 0.68 - - - low
RDS 0.18 0.81 0.6,1.1 11% 1.34 - - - low
S 0.03* 0.64 0.43,0.95 55% 2.21 Dang 2019 0.42 - low