The Success Rate of Intrauterine Insemination

Peter Kovacs, MD, PhD


March 17, 2010

Predictive Factors for Pregnancy After Intrauterine Insemination (IUI): An Analysis of 1038 Cycles and a Review of the Literature

Merviel P, Heraud MH, Grenier N, Lourdel E, Sanguinet P, Copin H
Fertil Steril. 2010;93:79-88


Infertility is defined as the inability to achieve a pregnancy following a year of trying spontaneously. Infertility affects about 10%-15% of the reproductive-age population, although the rate depends on the age of the women as well. Infertility is less frequent among younger women and more prevalent among older women. When a couple is unable to achieve a pregnancy, an evaluation is performed; on the basis of this evaluation and the personal history of the couple, a treatment plan can be established.

For the woman with an ovulatory problem, unilateral tubal disease, cervical origin early-stage endometriosis, or in whom no identifiable causes (so called unexplained infertility) can be found, intrauterine insemination (IUI) with or without controlled ovarian hyperstimulation (COH) is typically recommended. This treatment has several benefits. The medication requirement is low, monitoring is minimal, the procedure is noninvasive, the laboratory needs are not too complex, and most importantly it is inexpensive. On the other hand, the efficacy is not very high. A healthy young couple attempting to become pregnant naturally has about a 25% chance of success during each cycle. IUI pregnancy rates are in the range of 10%-20% (per cycle), and cumulative pregnancy rates are in the 30%-45% range.[1,2,3,4] Besides the relatively low success rates, another problem with IUI is the risk for multiple gestations, especially high order multiple gestation, when the growth of multiple follicles is induced.[5]

The alternative to IUI is in vitro fertilization (IVF). IVF is more invasive and requires closer monitoring, more medications, and special laboratory tests. Costs are significantly higher as well. For all this, the couple gets a several-fold higher pregnancy rate and, with the transfer of an appropriate number of embryos, a relatively low multiple (especially high order multiple) pregnancy rate. Success is the most important parameter for patients; therefore, the patients to whom IUI is offered and the number of recommended attempts must be carefully selected.

Study Summary

This retrospective analysis assessed predictors of IUI success in 1038 cycles in 353 patients. Gonadotropin stimulation was used in all patients, and the luteal phase was supported by vaginal progesterone. Patient variables (age, follicle-stimulating hormone [FSH] level, order of treatment cycle, semen characteristics, COH use), stimulation outcome (number of follicles, estradiol level), and IUI techniques were analyzed. The mean age of the patients was 31 years, and the mean body mass index was 23. Most inseminations followed ovulation induction with human chorionic gonadotropin, and spontaneous luteinizing hormone surge occurred in about 10% of the cycles. Pregnancy resulted from 14.7% of the cycles, and 80% of these were ongoing pregnancies. The per-cycle pregnancy rate started to decline after the third attempt, and no pregnancies were reported after the sixth cycle. Pregnancy was achieved with IUI by 40% of the couples. More than 80% of these pregnancies were achieved during the first 3 cycles.

Age was a strong predictor of success (38.5% in women under age 30 vs 12.5% in those over age 40). The patient's baseline FSH level had no predictive value. Patients with ovulatory or cervical problems were the most likely to conceive with IUI. Patients with higher (> 500 pg/mL) estradiol levels and with > 1 follicle over 16 mm were more likely to achieve a pregnancy. Higher total motile sperm count was also associated with better chance for pregnancy. The investigators concluded that patients with ovulatory dysfunction or cervical infertility, producing 2 or more dominant follicles with an estradiol level in excess of 500 pg/mL, are the most likely to have a successful IUI treatment. The use of a soft catheter and a total motile sperm count more than 1 million are also associated with higher success.


Under the right circumstances, IUI can be a successful, easy, and safe infertility treatment option. Multiple factors need to be assessed when deciding about the choice of treatment. The patient's age, the duration of infertility, ovarian function, etiology of infertility, semen characteristics, the status of the tubes, and the presence of other gynecologic or medical problems all have to be considered. The 2 most important benefits of IUI are the simplicity of the treatment and the low cost. When they are well-informed, patients generally accept the use of a lower efficacy treatment. The provider, however, must be aware of how desperate some of these couples are. They frequently do not care about the difficulty of treatment or even the expense (especially if the treatment is reimbursed), but after years of failure and negative results they wish to achieve a pregnancy as soon as possible. Keep in mind that IUI treatment attempts should not be excessively prolonged because this will only add further to the psychological burden of infertility. Because success rates with IUI are rather low in women over 40 years of age, it might be preferable to proceed directly to IVF in older women. In women under 40 years of age, 3-4 cycles should give a reasonable chance to achieve a pregnancy, and if the patient is open to other types of treatment after this many cycles of IUI, IVF should be recommended.[1,2,3,4] In women with anovulatory cycles or when donor sperm is used, IUI can be attempted up to 6 times.[1] This study also indicates that in well-selected cases, IUI can be an effective treatment, achieving a near 40% pregnancy rate per couple. It is important to understand the psyche of the infertile couple and avoid continuing a low efficacy treatment for too long before proceeding to a more effective treatment such as IVF.



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