Increasing shortness of breath

Jessica
Anyone else experiencing an increase in shortness of breath? I'm 37 weeks today and have been keeping active throughout the pregnancy with cardio kickbox once or twice a week, walking, hand weight workouts (only 5-7.5 lbs), and step aerobics. I usually work out 4-5x per week, pacing myself, drinking a lot of water, and taking breaks when needed. However when I hit 36 weeks, my energy seemed to dip and even just walking can cause shortness of breath and slight heart palpitations if I push it too hard. Walking up steps is worse. I was going to try to keep up with my typical workouts but it seems I'll need to scale down. I eat a pretty healthy diet for the most part. Protein, fruits and veggies, healthy fats, nuts, seeds, grass fed yogurt, appropriate seafood, etc. 
Best of wishes and God bless all of us new moms as we get through these final weeks of pregnancy! I pray all of your deliveries are as smooth and healthy as possible!