OBJECTIVETo investigate the main correlative factors affecting the pregnancy rate of intrauterine insemination (IUI) by means of analyzing 186 patients and 216 cycles of IUI.

METHODSComparisons were made between different pregnancy rates from five respects: infertility reasons, stimulation and natural cycles, different protocols for stimulating ovulation (CC group, CC + hMG group, hMG group), two methods for semen treatment (swim-up and gradient centrifugal), and insemination time (endometrial thickness and E2 levels at the day of hCG injection, and times of IUI).

RESULTSThe pregnancy rates resulting from male and cervix factors (29.82%, 25.00%) were significantly higher than those from other factors. There were few statistical differences in the pregnancy rates between stimulation and natural cycles (19.54% vs 16.67%), between the three different protocols for stimulating ovulation (CC 6.50%, CC + hMG 14.28%, hMG 22.30%), between gradient centrifugal and swim-up methods (20.13% vs 16.13%) and between one-time IUI and two-time IUI (19.73% vs 17.39%) (P > 0.05). However, the pregnancy rates were statistically correlated with the endometrial thickness at the day of hCG injection and different E2 levels of the follicles over 14 mm in diameter (P < 0.05).

CONCLUSIONIUI is of more applied value for infertility caused by male and cervix factors. With these factors in view, to choose the most suitable insemination time is the key to increasing pregnancy rate.