I am 23 weeks pregnant today. Yesterday I was at my Primary with a sinus infection. I took a pulse-ox test which was 97% resting. After walking only a few minutes it dropped down to 90% and felt kinda hard to carry on a conversation with the nurse any longer. After returning to the room to sit, it jumped right back up to 97% again. Am I doing harm to the baby, just by walking around my house? How long can I be "up and around" at the 90% mark without doing damage? Added info: I have a ventricular heart murmur and recently moved to a higher altitude (6,000ft). Could that have any impact. (asking because ob/gyn's nurse won't return my call)