A wind turbine blade comprising a profiled hollow contour, at least one reinforcing beam (15) placed between two shell body parts (13, 14), the beam comprising a first beam flange (16a) and an opposing second beam flange (16b), a beam body (17) connected to the first beam flange (16a) by a first transition area (32a) and connected to the second beam flange (16b) by a second transition area (32b). The beam body comprises a beam core (22). The beam core (22) comprises a first outer core surface (24a) and an opposite second outer core surface (24b). The beam body further comprises a web (50) arranged on the outer core surfaces. The flanges (16a, 16b) and the web (50) are made from a fiber-reinforced polymer. The transition areas (32a, 32b) comprise notch-reducing mean formed of rounded corners of the beam core (22).