Hi,
After I read your question the first thing that stuck out to me was when you stated that both you & your partner have concieved with your ex partners. This is important because sometimes couples can suffer from an immune disorder thus making the female "allergic" to her partners sperm. When your partner ejaculates inside you your body responds by attacking his sperm because your body considers the sperm a foreign body. A postcoital test is the diagnostic test of choice. Good luck hope this hels.
Hi!
Your partner should go to see a urologist. In some cases the sperm count can be increased by using medications. Aritficial insemination is another option that helps concentrate the good sperm, and since you are 39, it might be a good option for you. If you are not having success fairly quickly you should consult with a fertility specialist.
If you want to go it alone, there is a supplement called Proxeed that you can purchase on line.
Good luck!
Dr B