HI!! FIRST OF ALL – CONGRATS!! Great question – apologies that wasn’t more clear in the initial post!
‘Neurologically Taxing’ training movements are exercises with a load or volume done above 90% rate of perceived exertion or roughly around a 1-5 rep max. So big lifts such as deadlifts, squats, chest press done at a volume where you have lower reps for higher weight may be something to reconsider if you’re feeling super tired. In pregnancy, your focus for the gym shouldn’t necessarily be training for volume or performance, but rather maintenance and quality movement. My recommendation is rep ranges of 12-15, ending at 80-85% RPE.