Inclusion Criteria:  Female subject 18 years (≤) age (≤) 38 years Patient scheduled for a blastocyst frozen transfer (vitrification on Day 5) on HRT cycle (hormone replacement therapy) Measurement of the two uterine PI (pulsatility index) greater than 3 (> 3) at the first monitoring Dm (corresponding to Day 13-Day 16 of the cycle) BMI ≤ 30 kg / m2 Carrying out a transfer test qualified as easy (passage through the cervix of a flexible or rigid catheter, without anesthesia or Pozzi forceps) Collection and signature of free and informed consent Subject affiliated to or beneficiary of a health insurance plan  Exclusion Criteria:  Active smoker patient (at least one cigarette a day at the enrollment in the study) Oocyte recipient patient A pre-implantation genetic screening (PGS) is planned for the patient Patient with stage 3 or 4 endometriosis, or adenomyosis Contraindication to the use of amlodipine (recent myocardial infarction less than one month old, severe angina pectoris, severe hepatic insufficiency, treatment with ciclosporin, hypotension, hypersensitivity to amlodipine, dihydropyridine derivatives) Concomitant use of inhibitors or enzyme inducers of CYP3A4 Patient already being treated for high blood pressure Patient with an ovarian follicle recruitmant (> 12mm) during the first monitoring (the most conservative case) Patient participating in another human intervention study Patient in the exclusion period determined by a previous study Patient has already participated in this study Patient under legal protection, guardianship or curatorship Impossibility to give the patient clarifying information Impossibility to perform monitoring by an experienced sonographer Breastfeeding patient according to article L1121-5 of the CSP Patient protected or unable to give consent according to article L1121-8 of the Public Health Code (CSP) Vulnerable person according to article L1121-6 of the CSP