Study characteristics
A total of 20 studies participated in NMA comprising 4461 women (vaginal
progesterone 1081, 17-OH progesterone 530, pessary 828, pessary plus
progesterone 43, control group 1979). Twelve studies had progesterone as
the main intervention: seven studies compared vaginal progesterone
(varied between 90mg, 200mg, 400mg and 600mg) vs control group (placebo
or standard treatment).30-36. Five studies compared
intramuscular progesterone vs control group. The 17-OH progesterone dose
varied between 250 to 1000mcg37-41.
Eight studies had cervical pessary as the main intervention: six studies
compared pessary vs control group9,42-46, one study
compared vaginal progesterone vs pessary47 and one
study compared the combined intervention pessary + vaginal progesterone
vs progesterone8. Table 1 shows the descriptive
characteristics of the included studies. The full quality assessment
result of the included studies using Rob2 is reported in Table S2.
Considering the study’s results including participants with a CL cut-off
point (total sample or specific a subgroup), one study included women
with CL ≤ 15mm30, three studies included CL ≤
25mm41,43,44, one study included CL<
30mm36, two studies included CL ≤
30mm8,45 , studies included CL
<35mm9,40, one study included
CL≤35mm46, one studiy included
CL<38mm40 and eight studies included
CL<40mm31-35,37-39.
Table 1 - Main characteristics of studies included in network
meta-analysis