“…Women with thin endometria have lower pregnancy rates, largely related to implantation failure 1, 2, 3, 4, 5, 6. The authors recently found high blood impedance in the uterine radial artery in patients with a thin endometrium4 and that vitamin E, L‐arginine, and sildenafil citrate treatments, which increase the blood flow of the uterine radial artery, helped to thicken the endometrium 7. This suggests that a low level of blood flow to the endometrium reduces its thickness, although it remains unclear why this would result in implantation failure.…”