ABSTRACT
Objective To investigate the expression of endometrial leukaemia inhibitory factor（LIF） gene in patients with unexplained infertility. Methods By a quantitative reverse transcription-polymerase chain reaction (RT-PCR)，the expression of LIF gene on endometrium during mid-luteal phase was detected in 35 unexplained infertility (infertility group) cases and 20 infertile cases due to tubal obstruction or male factor (control group). Results The level of LIF mRNA expression on endometrium during mid-luteal phase in infertility group was 0.448±0.239，significantly lower than those in the control group （1.093±0.761，P<0.01). Conclusions Our findings suggested LIF might play an important role in the process of implantation. The decreased expression of LIF gene might be one of the major causes of unexplained infertility.