Hi, Thanks for posting in HCM. I understand your concern. Letoval contains letrozole as ingredient. It reduces the amount of estrogens. This it helps to counter hyperestrogenic state and aids in ovulation process. It s side effects include: inflammation of mouth or lips, increased urinary frequency, dizziness, hair loss, increased blood pressure and breathlessness. Duphaston contains dydrogesterone, which is a synthetic progesterone. It is used to treat conditions where there is lack of or insufficient quantities of endogenously produced progesterone. It s side effects include: nausea, bloating, breast pain, dizziness, irregular bleeding and weight gain. However, these side effects are only possible and does not always occur. Letoval medication is given so that ovulation occurs at proper time. If you follow the instructions, and if fertilization occurs, duphaston would help in the process of implantation and progression of pregnancy. Kindly follow the advise as suggested and do the necessary follow-up. Hope the information provided would be helpful. All the best. Regards, Dr.Ashakiran.S. MBBS., MD.