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Source: Zarek SM, et al. Single-donor and double-donor sperm intrauterine insemination cycles: Does double intrauterine insemination increase clinical pregnancy rates? Fertil Steril 2014;102:739-743.
To determine whether a single or double intrauterine insemination (IUI) improves pregnancy outcomes, the authors used a retrospective cohort design in a large private practice fertility center to observe clinical pregnancy rates after a natural or stimulated cycle. A total of 3159 donor IUI cycles were studied, of which 673 single and 2486 double inseminations were performed. Only cycles utilizing donor sperm were included in the evaluation and no other exclusions were used. Prior to each insemination, frozen donor sperm was thawed and washed to remove the seminal fluid; then the supernatant was re-suspended in sterile media. A catheter containing the sperm was placed directly into the uterus, bypassing the vagina and cervix to concentrate the male gametes in an area closer to the fallopian tubes. Timing of the insemination cycle was done using a urinary test kit to detect the luteinizing hormone (LH) surge or following injection of human chorionic gonadotropin (hCG) to mimic the LH surge. The two study groups (single or double) were similar in age, body mass index, number of cycles prior to the study, chance of having diminished ovarian reserve, and type of cycle (natural vs stimulated). Whether a patient underwent a single or double insemination was up to the physician and patient. Utilizing univariate regression and generalized...