According to a study in the American Journal of Respiratory and Critical Care, breathlessness can be due to inflammation in the body, and, in some cases, estrogen can play a role in inflammation.  As you are likely aware, estrogen levels fluctuate during a woman’s cycle and can be more dramatic as she moves through perimenopause and into menopause.

Also, on a concurrent note, a study by the journal Cognitive Behavioral Therapy, was done on regularly menstruating females to determine their CO2 sensitivity during the phases of their cycles.  It found that a woman’s sensitivity to CO2 increased during the luteal phase, or the phase leading up to her menses.  Progesterone levels rise during the luteal phase, and progesterone is a respiratory stimulant.  In other words, breath rate can change during the phases of a woman’s cycle as hormones fluctuate.  If progesterone can stimulate a faster breath cycle, this can drop the CO2 levels, and in a...