Table 4.

Summary of findings table

*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI)

CI, confidence interval; MD, mean difference; OR, odds ratio

GRADE Working Group grades of evidence

High certainty: We are very confident that the true effect lies close to that of the estimate of the effect

Moderate certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different

Low certainty: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect

Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

^aOne RCT and 2 retrospective cohorts with low/moderate risk of bias. Main reason for downgrading is the study design

^bMost studies are cohorts and before-after, and four with serious/critical risk of bias. Main reasons for downgrading are limitations due to study design and confounding

^cOne RCT and one retrospective cohorts with moderate risk of bias. Main reason for downgrading is the study design

^dConfidence interval is wide, showing that LPS could reduce slightly the cancelation rate or increase it a lot

^eTwo cohort studies with critical risk of bias (the larger with 90% of the weight is retrospective). Main reasons for downgrading are limitations due to study design and unbalanced confounding

^fConfidence interval is wide, showing that LPS could increase or have no effect on liver birth rate

^gOne RCT with unclear risk for randomization method and allocation concealment and one before-after cohort with critical risk of bias. Main reason for downgrading is the study design

^hOne RCT with unclear risk for randomization method and allocation concealment and one retrospective cohort with moderate risk of bias. Main reason for downgrading is the study design

ⁱConfidence interval is wide, showing that Double stimulation could reduce or increase the clinical pregnancy rate

^jConfidence interval is wide, showing that Double stimulation could reduce or increase the miscarriage rate

^kOne small prospective cohort with moderate risk of bias. Main reason for downgrading is the study design

^lConfidence interval is wide, showing that Double stimulation could make little or no increase in live birth rate, or it could be a large increase in live birth rate

^mOne small retrospective cohort with critical risk of bias. Main reason for downgrading is the study design and limitations in confounding

ⁿConfidence interval is wide, showing that Double stimulation could reduce or increase the cancelation rate