is there, it is difficult to determine the period of ovulation naturally. Since you have tried 3 cycles of IUI already, I would suggest you to check the patency of your tube also. The best method to check for ovulation is Scan- follicular study
.Since your husband's semen motility is low, there are certain medicines (anti oxidants) which improves the motility. Since you had one pregnancy
earlier, you have high chance of getting pregnant. All the Best.