Study Design
This retrospective study included women who underwent IUI with donor sperm in a natural menstrual cycle. The trial was conducted between January 2012 and December 2017 at the Center for Reproductive Medicine of the Shandong Provincial Hospital Affiliated to Shandong University. The Institutional Review Board approved the research project.
Prior to the IUI cycles, all women underwent basic fertility investigation that included evaluations of the following: cycle day 3 FSH, LH, estradiol, anti-Müllerian hormone (AMH), prolactin, and thyroid stimulating hormone (TSH) levels, hysterosonography (at least one month prior to IUI), as well as transvaginal ultrasound for evaluation of pelvic anatomy and follicular monitoring.
Study inclusion criteria were: age ≤ 35 years, regular menstrual cycles (28–35 days), no personal history of infertility or medical conditions likely to cause infertility, a normal baseline hormonal profile, and patency of at least one fallopian tube. Exclusion criteria were the presence of irregular menstrual cycles, tubal factor infertility, confirmed endometriosis, a diagnosis of polycystic ovarian syndrome (according to the Rotterdam criteria; Rotterdam ESHRE/ASRM-Sponsored PCOS Consensus Workshop Group, 2004), abnormal TSH or prolactin levels, or any known metabolic or endocrinological disease. Women with incomplete medical records were excluded from the study, as were women who taking any medication.
The choice to use hCG trigger or urinary LH monitoring plus transvaginal ultrasonography was made according to the patient’s preference and availability for monitoring. A home urinary ovulation prediction kit was used to monitor urinary LH levels once a day, in the evening around 19:00 h, starting on cycle day 10. And serial ultrasonography for follicular monitoring was also started on cycle day 10 for all cycles. When ovulation was diagnosed, insemination was performed immediately.
In the spontaneous ovulation group (based on urinary LH monitoring and transvaginal ultrasonography), insemination was carried out within 24 hours after detection of the first urinary LH positive test or upon detection of ultrasound features suggestive of ovulation. In the induced ovulation group (administration of hCG trigger), when a leading follicle reached a diameter of 16 mm or urinary LH surge appeared, ovulation was triggered using 10,000 IU of recombinant hCG (choriogonadotropin alfa, Ovidrel®; EMD Serono, Inc.). In our practice, the standard of care is to perform two inseminations in a given cycle, approximately 24 hours and 36 hours after HCG injection 13-15; however, there are clinical factors affecting the clinical decision to use single or double IUI including patient demand, financial barriers, or ovulation time.
Frozen donor sperm were obtained from the Shandong Province Human Sperm Bank of China, and were thawed on site on the day of insemination. All sperm samples were prepared with a density gradient centrifugation method using Puresperm TM (Nidacon, International AB)16. The quality of semen was evaluated before and after processing (semen TMS).
The insemination procedure was the same for all women, bed rest was maintained for 15 min after the insemination 17. A urine pregnancy test was administered 14 days after insemination, and if positive, a transvaginal ultrasound would be performed 14 days later to assess the pregnancy outcome (including the number of gestational sacs, viability, and location).