I went for a check up today. I am 13w 5d. The dentist tipped me right back so that my head was lower than my body. I was only there for about 3-4 mins but found that I kept holding my breath while I had my mouth open. When I got up I was a bit dizzy and had flashing spots in front of my eyes.
Was this from holding my breath or being almost upside down. I know that you shouldn't lay on your back but don't know if this is more advice for later on in pregnancy.