Hallow Dear, Hormonal levels is one of parameters that suggest that the follicles are maturing normally and they are releasing eggs (ovulating). However, the size of the follicle and the thickness of the endometrium do play important role in successful implantation and pregnancy. These two parameters can be studied by ovulation monitoring by ultrasonography. Follicles of size between 18 mm and 21 mm size release healthiest eggs and these eggs after fertilization are known to have good pregnancy success rate. Follicles which ovulate at a smaller size or larger size do not have good successful pregnancy rate. Similarly the endometrial thickness is also very important. Endometrium of thickness between 9 mm and 14 mm is highly conducive for successful implantation of the fertilized ovum (blastocyst). Hence, I would suggest you to study these two factors before undergoing IUI. In fact, IUI should be monitored and guided by ultrasonography directed ovulation monitoring. I hope this helps you. Dr. Nishikant Shrotri