WEBVTT 00:00.000 --> 00:02.067 During the third trimester of pregnancy, 00:02.100 --> 00:05.433 rapid brain growth consumes more than 50% of the energy 00:05.467 --> 00:09.000 used by the fetus. 00:09.033 --> 00:14.867 Brain weight increases between 400 and 500%.