Ten studies were included in the review.
Embryos derived from oocytes in which the meiotic spindle was viewed had a statistically significant higher fertilisation rate (OR 1.79, 95% CI 1.57 to 2.05; nine studies), PN-stage embryo morphology (OR 1.71, 95% CI 1.20 to 2.44; two studies), cleavage rate (OR 1.85, 95% CI 1.47 to 2.32; three studies), day-3 embryo-stage quality (OR 1.70, 95% CI 1.20 to 2.42; three studies) and number of embryos that reached blastocyst stage (OR 2.61, 95% CI 1.74 to 3.91; two studies) compared to oocytes that showed no meiotic spindle.
There were no differences for implantation rate or clinical pregnancy transfer rate between embryos derived from oocytes in which the meiotic spindle was viewed compared with oocytes that showed no meiotic spindle.
Significant heterogeneity was reported for the comparison of fertilisation rate (I2=86.6%); a random effects model did not change the significant outcome. Heterogeneity was not detected for other comparisons.