Hello Thanks for writing to us with your health concern. Normally, in a 28 day cycle, ovulation occurs on day 14. By this time, the mature egg follicle, which is ready to rupture, should measure around 18 - 20 mm. The egg follicle grows at a rate of 1 - 2 mm per day so by day 12, it should be around 12 mm or more. In your case, it is not of the optimum size on day 12. However, some women have delayed cycles or delayed growth of the egg follicle. In that case, the egg will grow at a normal pace, only the day would be late. Continue having follicular monitoring for a few more days. If the follicle size becomes optimum, then there would be scope for ovulation. Ovulation ( rupture of the egg follicle ) also is confirmed via the follicular ultrasound scan. Once ovulation is confirmed, please remain sexually active to maximize the chances of pregnancy. Take regular folic acid supplements. Also, if 3- 6 such cycles of stimulation fail inspite of good ovulation, then go for laparoscopy to check the patency of your fallopian tubes. All the best Take care.