Inclusion criteria:
1.Women 18-40 yr with BMI<38 undergo ICSI treatment and freeze embryo transfer candidate are participated in this study.2. Blood pressure >= 100/60, 3. FSH <14mli/IU. 4. abnormal uterus in HSG or hystroscopy. 5. who do not contraindicate the use of nifedipine, such as heart and liver 6. Patients who do not have a history of irregular heart rate or who do not use hypotention medication.
Exclusion criteria:
Patients who have been taking medication with nifedipine over a month have interfered with drugs such as benzodiazepines, flecainide, imipramine, propafenone, azole antifungals, cimetidine, cyclosporine, erythromycin, quinidine, terfenadine, warfarin and theophylline. 2.Those who have blood pressure of 60/100 (mmHg) or less before embryo transfer