Determinants of the outcome of intrauterine insemination: analysis of outcomes of 9963 consecutive cycles.
OBJECTIVE
Our aim was to determine which factors influence the effectiveness of intrauterine insemination.


METHODS
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 <26 years old conceived, compared with 13.9% of those 26-30 years old, 12.4% of those 31-35 years old, 11.1% of those 36-40 years old, 4.7% of those 41-45 years old, and 0.5% of 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.


CONCLUSIONS
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.
Stone
B A
BA
Institute for Fertility Research, Santa Monica, CA, USA.
Vargyas
J M
JM
Ringler
G E
GE
Stein
A L
AL
Marrs
R P
RP
D000328:Adult; D000375:Aging; D005260:Female; D006801:Humans; D007317:Insemination, Artificial, Homologous; D008297:Male; D006080:Ovarian Follicle / Q000033:anatomy & histology; D010060:Ovulation; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D013076:Sperm Count; D013081:Sperm Motility