In this study the investigators took the opportunity of having a large sample of IUI cycles in a single centre to try to analyse the effect of stimulation protocols and of the infertility origin on the results, taking in account the main confounding variables (female age, IUI attempt rank, and sperm quality) on the clinical outcome.

All couples had undergone a standard infertility evaluation, which included medical history, physical examination, and assessment of tubal patency by either hysterosalpingography or laparoscopy and hormonal analysis on cycle day 3. A transvaginal ultrasound scan was performed on the second day of the cycle. On the same day, ovarian stimulation was carried out with recombinant FSH (follitropinrFSH; Gonal-F, MerckSerono, France, orfollitropin;Puregon, MSD, France), urinary FSH (urofollitropin, Fostimon, France), orhMG (menotropin, Menopur, France) atastarting dose of 75 IU/day from the second day of the cycle.

The main clinical outcome measures were clinical pregnancy and live-birth rates per cycle. Clinical pregnancy was defined as the evidence of pregnancy by ultrasound examination of the gestational sac at weeks 5-7.

Many studies have evaluated the predictive factors of IUI clinical outcomes, including the female's age, the infertility duration, the rank of the attempt, and the sperm parameters [10-16]. However, few studies have compared the pregnancy rates based on the used COS or on the infertility type.

In this study the investigators took the opportunity of having a large sample of IUI cycles in a single centre to try to analyse the effect of stimulation protocols and of the infertility origin on the results, taking in account the main confounding variables (female age, IUI attempt rank, and sperm quality) on the clinical outcome.

All couples had undergone a standard infertility evaluation, which included medical history, physical examination, and assessment of tubal patency by either hysterosalpingography or laparoscopy and hormonal analysis on cycle day 3. A transvaginal ultrasound scan was performed on the second day of the cycle. On the same day, ovarian stimulation was carried out with recombinant FSH (follitropinrFSH; Gonal-F, MerckSerono, France, orfollitropin;Puregon, MSD, France), urinary FSH (urofollitropin, Fostimon, France), orhMG (menotropin, Menopur, France) atastarting dose of 75 IU/day from the second day of the cycle.

The main clinical outcome measures were clinical pregnancy and live-birth rates per cycle. Clinical pregnancy was defined as the evidence of pregnancy by ultrasound examination of the gestational sac at weeks 5-7.

Inclusion Criteria:

• women with a failure to conceive after, ≥12 months of unprotected and regular intercourse,
• aged 20-44 years
• with normal ovulation reserve (basal follicle- stimulating hormone (FSH) level < 10 IU/l and estradiol (E2) level < 30ng/mL);
• theirpartnershadtohaveatotal motile sperm (TMS) count of>1×106.

Exclusion Criteria:

• TMS ≤1×106;
• sperm donation;
• seropositivity for human immunodeficiency virus (HIV) for any couple member;
• inseminations performed in a natural cycle or with clomiphene citrate (CC)

All couples attending our reproductive medical center to obtain homologous IUI program with COS between January 2007 and August 2014 ll couples had undergone a standard infertility evaluation, which included medical history, physical examination, and assessment of tubal patency by either hysterosalpingography or laparoscopy and hormonal analysis on cycle day 3.