Ectopic pregnancy rates after frozen versus fresh embryo transfer: a meta-analysis.

BACKGROUND/AIMS: The aim of this meta-analysis was to determine whether frozen embryo transfer (ET) increases ectopic pregnancy (EP) rate compared with fresh ET.

METHODS

A meta-analysis was performed of data from seven comparative studies including 13,059 pregnancies that resulted from nondonor in vitro fertilization cycles.

RESULTS

The EP rate was 2.31% (49/2,125 pregnancies) for frozen ET and 1.48% (162/10,934 pregnancies) for fresh ET. These rates were statistically not different when assessed either by random (OR 1.66, 95% CI 0.62-4.41) or fixed effect model (OR 1.17, 95% CI 0.84-1.63).

CONCLUSIONS

The combined data presented in this meta-analysis do not support an increased risk of EP following frozen ET compared with fresh ET. However, as there was a substantial heterogeneity among the studies analyzed, the authors consider that further well-designed studies controlling for several potential biases which could affect the EP risk should be conducted.