Statistical analysis
Meta-analyses were carried out using STATA Meta-Analysis (V2.0, Biostat,
Englewood, NJ, USA). The RoB graph was drawn by Review Manager 5.3
(Cochrane Collaboration Software, RevMan). The measure of treatment
effect was calculated by the pooled odds ratio (OR) with 95% confidence
intervals (CI) with random effects models. Intention-to-treat (ITT)
analysis would be used when available. The number of trials in
meta-analysis might not always be 49, because the included studies had
multiple treatment or control types and the meta-analysis was undertaken
based on each comparison.
Subgroup and meta-regression analyses were predefined with respect to
age of participants (<35 or ≥35 years (28) ), different
acupuncture types, type of control (no treatment or sham/placebo
control), acupuncture timing (two types were categorized: type A, the
acupuncture was performed around the time of ET (embryo transfer), which
referred to the acupuncture treatment performed before and after ET
(29); type B, before the ET); geographical origin of the study (Asian or
not Asian), whether or not RIF (repeated IVF failure), acupuncture
sessions (1, 2 or more than 3 sessions). Otherwise, the clinical
characteristic previously was found to benefit trials with lower
baseline pregnancy rates (20, 30), therefore, the stratified analysis
was conducted by the pregnancy rate of no treatment group. Sensitivity
analyses were also conducted to explore the robustness of the pooled
effects of included studies: (1) restricting CPR results to the studies
which simultaneously reporting LBR; (2) limiting the studies with low
risk of bias; (3) deleting the studies whose primary outcome was not to
evaluate the effects of acupuncture on pregnancy rates from IVF.
Heterogeneity was assessed using the I 2 test.
Publication bias were shown by a funnel plot and assessed by the Egger
weighted regression methods (p < 0.05 was considered
statistically significant).