suzipete, I am a man, so don't know about pregnancy. What I know about COPD is I have bronchiectasis, a form of COPD. I had it since 1994. Yes, I had many infections, and many hospital stays. I believe that exercise, whichever form it takes, will maintain your body and lungs. it might even improve your lungs. Briefly, i was on oxygen in 2010 with TB and pneumonia. Within a month at the gym, i was off the oxygen. I still go regularly at the gym and feel fine (no TB after 2 1/2 years of drugs, no pneumonia, that was easy to treat!).
Now, there are numerous exercises and I think you should explore exercises for COPD. You could explore Chinese Qigung, which is the medical martial arts (gentle, that is) I do one series called the 8 pieces of brocade - brocade being silk is supple, yet sturdy, which is the aim of the exercises, coupling it with the all important breathing.
I've just read that there is something call the hundred up, which are running exercises at home - on the spot.
But the benefit of exercise is not only to maintain your health, but to give you confidence. If you wanted a child, I wouldn't delay too much at 37. You have the option to maintain your health, so you can explore with your conscience and your hubby the pros and cons of a baby. Of course, (as my mum testified) a growing baby demands a lot of your energy and your life. It's also the most miraculous event in your life.
(my wife and I decided not to have children on account of her and my disability. where both of us were disabled - she with bipolar with schizo-affective disorder; me with bronchiectasis, we thought it wouldn't be fair on a child. I miss one, to tell you the truth, even as a man!) Your quest is a serious and complex one. You best bet is to gather lots of information about your condition and your circumstances. Somehow, don't forget there's one big part in this, it is love! that may rule over all. Be wise! Ask a lot of questions. Best wishes. Mic