Nimodipine to Prevent LH Surge During Ovulation Induction: Blinded Placebo-controlled RCT

Inclusion Criteria: * Age 25-40 years at the time of enrollment * Both ovaries intact by history and ultrasound assessment * Early follicular phase (day 2-4) serum FSH level \<20 mIU/mL * Diagnosis of subfertility with a recommended treatment of COH and IUI * Providing written informed consent in English Exclusion Criteria: * Body mass index (BMI) \>38 kg/m2 * Early follicular phase (day 2-4) serum FSH level ≥20 mIU/mL * History of overstimulated cycle defined as \>3 mature follicles of ≥17 mm * Abnormal uterine cavity and/or tubal disease (as evidenced by sonohysterogram or hysterosalpingogram) * Diagnosis of infertility with a clear indication for in-vitro fertilization, such as bilateral tubal occlusion * Severe male factor infertility: Total Motile Sperm Count \< 2x106 post washing (sperm deemed inadequate for IUI preparation) * Any ovarian or abdominal abnormality that may interfere with adequate TV ultrasound evaluation * Absence of one or both ovaries * Any contraindication to being pregnant or carrying a pregnancy to term * Unexplained gynecological bleeding * Any medical condition that would jeopardize the patient or the integrity of the data obtained including: * Prior reaction or side effects from previous calcium channel blocker use * Any medical condition that may interfere with the absorption, distribution, metabolism or excretion of nimodipine such as hepatic disease, hypertension, seizure, concurrent infection, depression, reflux (see #12 below). * Mental health status resulting in cognitive or emotional impairment that would preclude study participation * The concurrent use of any of the following drugs: \[These medications have been shown to effect the availability of the medication or worsen hypotension symptoms\] * Antihypertensives (eg. ACE inhibitors, alpha-adrenergic blocking agents,methyldopa, beta-blockers, diuretics, PDE5 inhibitors, and other calcium antagonists) * Antiepileptics (eg. phenobarbital, phenytoin, carbamazepine or valproic acid) * Macrolide antibiotics (eg, erythromycin) * Azole antimycotics (eg, ketoconazole) * HIV protease inhibitors (eg, ritonavir) * Antidepressants (eg, nefazodone and fluoxetine) * Cimetidine * Patient unable to communicate adequately with the investigators and to comply with the requirements of the study * Unwillingness to give written informed consent