Objective: To evaluate the pregnancy rate in natural cycle, in ovarian stimulation by clomifene citrate, combination clomifene citrate with gonadotropins and gonadotropins alone. Design: A prospective study. Methods: From January 2001 to December 2004 we performed a total of 1747 AIH’s cycles (1124 in natural cycles, 296 cycles with clomifene citrate, 122 cycles clomifene citrate with gonadotropins and 205 cycles gonadotropins alone) and a total of 198 AID’s cycles (140 in natural cycles, 22 cycles with clomifene citrate, 13 cycles clomifene citrate with gonadotropins and 23 cycles gonadotropins alone). Results: In AIH’s cycles we achieved a total of 151 pregnancies (71 in natural cycles, 37 in cycles with clomifene citrate, 20 in cycles clomifene citrate with gonadotropins and 23 pregnancies in cycles with gonadotropins alone). The total pregnancy rate in AIH’s cycles was 8.6% (6.3% in natural cycles, 12.5% in cycles with clomifene citrate, 16.4% in cycles clomifene citrate with gonadotropins and 11.2 % in cycles with gonadotropins alone). Statistical difference was p<0.001, p<0.05 a p<0.05 respectively. In AID’s cycles we achieved a total of 40 pregnancies (27 in natural cycles, 5 in cycles with clomifene citrate, 5 in cycles clomifene citrate with gonadotropins and 3 pregnancies in cycles with gonadotropins alone). The total pregnancy rate in AIH’s cycles was 20.2% (19.3% in natural cycles, 22.7% in cycles with clomifene citrate, 38,5 % in cycles clomifene citrate with gonadotropins and 13% in cycles with gonadotropins alone). Statistical difference we didn’t reach. Conclusions: In AIH’s cycles we confirmed statistical difference between pregnancy rate in natural cycle, ovarian stimulation by clomifene citrate, combination clomifene citrate with gonadotropins and gonadotropins alone. Ovulation induction increases pregnancy rate compared with natural cycle. In AID’s cycles we didn’t confirmed statistical difference in pregnancy rate. Ovarian stimulation by clomifene citrate and intrauterine insemination remains the first choice treatment for ovulatory dysfunction, unexplained infertility, endometriosis, or male subfertility. Combination clomifene citrate with gonadotropins or gonadotropins alone may individualize ovarian stimulation.

        Key words: intrauterine insemination, pregnancy rate, natural cycle, ovulation induction, clomifen citrate, gonadotropins