I am 27 weeks pregnant and have been experiencing shortness of breath since appx 4 mos. It comes over me in spells including tachycardia while I m sitting or lying down. It is nearly impossible to get comfortable even with a focus on good posture for good diaphragm expansion. Sometimes I feel like I could pass out like yesterday while sitting in a chair at a restaurant with my friend. It is definitely worse after a meal, but I have noticed that it never occurs after I eat a bagel and cream cheese. I just don t understand why something that high on the glycemic index, not to mention how filling it is, would cause no problem compared to a cup of bean chili and half a portabella mushroom sandwich (yesterday s lunch). These spells sometimes last for a couple of hours. Dr says it s progesterone slowing down respiratory system. Perhaps it is, but why sometimes and not others. The SOB is not caused by physical exertion. I swim appx every other day without the anxiety of trying to catch my breath. Any ideas or do you agree it s just the hormones? Thank you for your time and consideration.