Ectopic pregnancy rates after frozen versus fresh embryo transfer: a meta-analysis.
OBJECTIVE
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.
Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seongnam, South Korea.
Byung Chul
BC
Jee
Chang Suk
CS
Suh
Seok Hyun
SH
Kim
D015925:Cryopreservation; D004624:Embryo Transfer / Q000009:adverse effects* / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods; D006801:Humans; D011247:Pregnancy; D018873:Pregnancy Rate; D011271:Pregnancy, Ectopic / Q000453:epidemiology*