Treatment in subjects is individualised and is monitored by serum estradiol (E2) measurements and ultrasound scans of the ovaries to assess the endometrial thickness. It has been observed in earlier studies that in OI for unexplained non-conception, induction of more than one follicle did not improve the ongoing pregnancy rate but increased the risk of multiple pregnancies. Therefore, to reduce the number of multiple pregnancies, in all IUI cycles for unexplained non-conception, monofollicular growth was suggested.