How often do couples get pregnant in their first 1 IUI cycle with gonal injections? And how many cycles does it usually take to be successful?

20 to 25% Gonadotropin IUI yields a pregnancy rate of approximately 20 to 25% per cycle. Within 3 to 4 cycles of the couples that are going to conceive 50% of them or more will be pregnant.
10-15% The success rate varies by age and other associated infertility factors. Studies show varied outcomes but the largest studies say about 10-15% per cycle. Tonal medication costs a lot more than Clomid (clomiphene) or Letrozole but probably not higher success rate. Talk with your specialist about choice of med and treatment.