Four prospective studies, which reported events but not the number of participants, were included in the review. Three studies were randomised and one study was a matched controlled trial.
L'Abbe's graph for heterogeneity was negative in both event rates of reproductive outcomes. Consistent effects were also demonstrated. Heterogeneity between the two groups was not statistically significant.
Pregnancy.
The pooled RR was 1.01 (95% CI: 0.95, 1.09, p=1.00) and the risk reduction was -1%. The pregnancy event rates that were consistently below the line of equality implied that the magnitude of effect was reliable. This corresponded to a RR of 0.75 (95% CI: 0.52, 1.06, p=0.99) for pregnancy and a risk reduction of 25% (95% CI: -6, +48).
The pooled ORs were 1.03 (95% CI: 0.90, 1.18, p=1.00) and 0.70 (95% CI: 0.47, 1.08, p=0.93) for cleavage and pregnancy rates, respectively.