I'm just in my second trimester, and I fainted on the MRT too! I need to get off and lie down after 30min of journey and reboard the train. Need to get the head level with the chest. Are you able to request to WFH? I work from home and go to lie down for 5 mins every few hours when I feel weak. Drinking isotonic drinks, juice and Milo helps as well.
sasi chello