Determinants of the outcome of intrauterine insemination: Analysis of outcomes of 9963 consecutive cycles

• Published in: American journal of obstetrics and gynecology 1999-06, Vol.180 (6), p.1522-1534
• Main Authors: Stone, Bronte A., Vargyas, Joyce M., Ringler, Guy E., Stein, Andrea L., Marrs, Richard P.
• Format: Article
• Language: English
• Subjects: Adult; Aging; Determinants of outcome of intrauterine insemination; Female; Humans; Insemination, Artificial, Homologous; Male; Ovarian Follicle - anatomy & histology; Ovulation; patient age; patient stimulation; Pregnancy; Pregnancy Outcome; Retrospective Studies; Sperm Count; Sperm Motility; sperm processing
• ISSN: 0002-9378
• DOI: 10.1016/S0002-9378(99)70048-7

Objective: Our aim was to determine which factors influence the effectiveness of intrauterine insemination. Study Design: This article is a retrospective statistical analysis of outcomes of 9963 consecutive intrauterine insemination cycles. Results: Patient age was the main determinant of pregnancy outcome (analysis of variance F ratio = 29, P < .0001), followed by the number of follicles at the time of intrauterine insemination (analysis of variance F ratio = 9, P < .0001) and sperm motility in the inseminate (analysis of variance F ratio = 4, P = .002). A total of 18.9% of all patients 45 years old ( P < .001). When analyzed by single years, ongoing pregnancy rates after intrauterine insemination remained high through age 32 years. Across all ages and causes of infertility, 7.6% of patients with 1 follicle at the time of intrauterine insemination conceived, compared with 10.1% with 2, 14.0% with 4, and 16.9% with 6 follicles ( P < .01). When ovulation occurred before intrauterine insemination (ie, no visible follicular structures), 4.6% of patients conceived. The likelihood of pregnancy was maximized when motile sperm numbers were ≥4 million and sperm motility was ≥60%. Differences in pregnancy outcomes between sperm processing options were related to differences in sperm motility after processing; use of methods incorporating motility enhancement with pentoxifylline and motile sperm concentration through silica gradients yielded the highest overall pregnancy rates. Conclusion: When the results of ongoing retrospective analysis of intrauterine insemination outcomes are applied, overall intrauterine insemination pregnancy rates have increased from 5.8% per cycle in 1991 to 13.4% per cycle in 1996, during which time the average age of patients undergoing intrauterine insemination has increased from 36.1 (±0.2) to 39.2 (±0.1) years. (Am J Obstet Gynecol 1999;180:1522-34.)