Hi,
I am taking heparin and aspirin before conception because my regular OB felt it was important to have thin blood at conception. My high risk OB said to start taking it as soon as I get a positive test. There are a lot of different schools of thought. I really think most doctors only advise aspirin preconception. I think some doctors wait until they see a heartbeat on ultrasound before giving you heparin. Taking the heparin can make you bleed a lot with your AF or a m/c. I have had both since being on the injections and the bleeding wasn't too bad. I have been taking baby aspirin daily for 5 months now. I started the heparin 2 months ago. I have not had any problems with it except some bruises and maybe a little dizzy the first week of injections.

Parker 7/20/07 @ 22 weeks
Shelby 5/27/08 @ 28 weeks
bean 9/5/08 @ 5 weeks