Uterine relaxation by sacral surface electrical stimulation on the day of embryo transfer.

The peak power of uterine peristalses after sacral surface electrical stimulation (ssES) treatment decreased markedly in comparison with that measured before ssES on the day of embryo transfer (ET). This suppression effect of uterine peristalses was stronger on day 5 of ET than on day 3. Because the uterus at the time of ET is sensitive to ssES, this electrical neuromodulation may be an effective method to induce uterine relaxation for ET.