Mine all four times was being very, very winded. With my first pregnancy I didn’t realize that was a symptom, and I had implantation bleeding that I thought was a short period. I ran a half-marathon and could not believe how winded I got. A week later, I was on a fairly easy hike and again was out of breath.
I didn’t take a pregnancy test until a few weeks later (when I missed a period). Was shocked.