[Risk factors associated with twin pregnancy in double embryo transfer].
OBJECTIVE
To explore the risk factors associated with twin pregnancy in double embryo transfer.


METHODS
A retrospective analysis was performed for 2970 double embryo transfer cycles, including 1984 cycles of fresh embryo transfer and 986 cycles of frozen-thawed embryo transfer (FET). Multiple factor Logistic regression was used. The twin pregnancy rate was studied in group of age < 35 or age ≥ 35 years old, in group of zero, single or double high-quality embryos transferred and group of fresh embryo transfer or FET cycles.


RESULTS
(1) There was a significantly negative correlation between women's age and twin pregnancy according to the analysis of multiple factor Logistic regression (P < 0.01). And a significantly positive correlation existed between the number of high-quality embryos transferred, FET and twin pregnancy (P < 0.01); (2) the twin pregnancy rate of both fresh embryo transfer and FET cycles was higher in group of age < 35 years than that in group of age ≥ 35 years (16.0% vs 8.0%, P < 0.01; 26.9% vs 14.2%, P < 0.01); (3) the twin pregnancy rate of fresh embryo transfer cycles with double high-quality embryos transferred was higher than that with zero or single high-quality embryos transferred (19.1% vs 5.4%; 19.1% vs 11.0%, P < 0.01); the twin pregnancy rate of FET cycles with double high-quality embryos transferred was also higher than that with zero or single high-quality embryos transferred (32.7% vs 10.8%; 32.7% vs 20.7%, P < 0.01); (4) the twin pregnancy rate of FET cycles was significantly higher than that of fresh embryo transfer cycles (24.7% vs 14.9%, P < 0.01).


CONCLUSIONS
Women's age, the number of high quality embryos transferred and FET are risk factors associated with twin pregnancy. At reproductive centers with a mature technique of FET, we recommend performing single high-quality embryo transfer in FET cycles to reduce the occurrence of twin pregnancy.
Affiliated Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310016, China.
Wei-hai
WH
Xu
Xiao-mei
XM
Tong
Hai-yan
HY
Zhu
Xiao-na
XN
Lin
Ling-ying
LY
Jiang
Song-ying
SY
Zhang
D000328:Adult; D015925:Cryopreservation; D004624:Embryo Transfer / Q000379:methods*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D015999:Multivariate Analysis; D011247:Pregnancy; D018873:Pregnancy Rate; D059285:Pregnancy, Twin; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult