Abstract
BACKGROUND: The causes of pregnancy failure after intrauterine insemination (IUI) are controversial. The purpose of this study was to investigate the influencing factors on clinical pregnancy after IUI. METHODS: This study retrospectively analyzed 1464 cycles of IUI performed at the Meizhou People's Hospital between March 2014 and June 2023. The χ(2) test and logistic regression analysis was applied to assess the associations between the some factors (maternal age, paternal age, cycle type (natural cycle or ovulation induction cycle), hormone level on the day of endometrial transformation (estradiol (E(2)), luteinizing hormone (LH), and progesterone (P)), endometrial thickness on the day of endometrial transformation, and forward motile sperm concentration after treatment) and pregnancy failure. RESULTS: Among the 1464 IUI cycles in this study, 268 cycles of assisted reproduction resulted in clinical pregnancy, with a clinical pregnancy rate of 18.3%. During the cycles with clinical pregnancy, there were 25 (12.9%) preterm births and 169 (87.1%) full-term births. The E(2) level on the day of endometrial transformation in clinical pregnancy group was higher than that in the pregnancy failure group (658.79±656.02 vs 561.21±558.83 pg/mL)(P=0.025). The clinical pregnancy group had a higher percentage of endometrial thickness between 8 and 13mm on the day of endometrial transformation than the pregnancy failure group (83.2% vs 75.0%)(P=0.002). The results of regressions analysis showed that low E(2) level on the day of endometrial transformation (<238.3 pg/mL vs ≥238.3 pg/mL: OR 1.493, 95% CI: 1.086-2.052, P=0.014), and endometrial thickness <8mm on the day of endometrial transformation (<8mm vs 8-13mm: OR 1.886, 95% CI: 1.284-2.771, P=0.001) may increase risk of pregnancy failure performed IUI. CONCLUSION: Low estradiol level, and endometrial thickness on the day of endometrial transformation may increase risk of pregnancy failure performed intrauterine insemination.