Ten RCTs (4,100 pregnant women, range 30 to 1,691) were included in the review. Four RCTs were regarded as having a low risk of bias. Four trials were judged to have a potential risk of bias. The risk of bias was unclear for two trials.
Anxiety (five RCTs, eight comparisons): Statistically significant reductions in anxiety were observed with the use of decision-aid tools compared with usual care (SMD -0.18, 95% CI -0.25 to -0.12; Ι²=0%). The results of subgroup analyses also showed significant reductions with decision-analysis tools (SMD -0.26, 95% CI -0.39 to -0.12; Ι²=0%; three RCTs), computer-based information programmes (SMD -0.30, 95% CI -0.50 to -0.10; one RCT), individual counselling (SMD -0.15, 95% CI -0.28 to -0.01; one RCT) and group counselling (SMD -0.12, 95% CI -0.24 to -0.00; Ι²=0%; two RCTs). No significant differences were observed with the use of decision trees (one RCT).
Decisional conflict - certainty (four RCTs, six comparisons): There were marginally significant reductions in decisional conflict observed for the use of decision-aid tools compared with usual care (SMD -0.16, 95% CI -0.32 to 0.00; Ι²=59%), with significant decreases observed for decision-analysis tools (SMD -0.23, 95% CI -0.37 to -0.10; Ι²=0%; three RCTs) and computer-based information tools (SMD -0.36, 95% CI -0.56 to -0.16; one RCT). There were no significant differences observed with group counselling (one RCT) and decision trees (one RCT) compared with usual care.
Decisional conflict - informed (three RCTs, four comparisons): There were no statistically significant differences observed between groups using decision-aid tools and usual care for informed decisional conflict. In addition, there were no differences observed between the use of computer-based information, decision-analysis tools or decision trees and usual treatment.
Impact on final outcome and final choice: There were no significant differences between groups using decision-aid tools and usual treatment for final outcome (four RCTs) or final choice (two RCTs). Subgroup analyses by tool type revealed no statistically significant differences between the groups.
Knowledge (seven RCTs, nine tools): Most tools showed increases in women's knowledge except for the decision tree (one RCT) and individual counselling (not evaluated).
The visual appraisal of funnel plots showed no evidence of publication bias for any outcome.