Post-training exhaustion

Im 23 Weeks and Ive noticed my stamina have significantly changed lately. Was active before pregnancy and continue running/rowing since Day 1. Today I trained on the rower for 20 minutes as usual then a 15 minutes musculation. Nothing too exhausting, during training I felt in the zone and I had a good nightsleep. Afterwards I ate a snack. Not half an hour later I crashed in front of the TV and snoozed like the entire afternoon!!! Is it like a growth spurt or does that mean its time to cut back on training?