Out of breath due to HRT?

[Katsite]

I started to take extremely low doses of hrt (progesterone and estradiol) almost a year ago. I get out of breath extremely quickly when I ride my bike. Is that because I

1. am a year older
2. am fatter because of the hormones (about 4kg) or
3. is it a side effect of the therapy?

I am just wondering if I need to see GP if it is 3. Anybody any similar experience?

Yes the breathlessness went away about 4 days after stopping the progesterone. I am on a synthetic progestin now that does not seem to cause it.