Hi Jessie,
Not sure if I can be much help, but for the first 20 weeks of my pg I was on heparin due to antibodies preventing me from getting pg. I was on asprin all the way through. Initally it was thought that I would be on heparin for the entire pg. Before it was decided that I could stop the heparin, my ob discussed the pros and cons of heparin and clexane at for different stages of the pg. I know he did think that I could go heparin, then clexane for the mid section then back to heparin, as I got closer to term, as the effects of heparin can be easily reversed in an emergency situation. Maybe talk to your ob/specialist about your concerns and options that you might have and the pros/cons of them.

In the end I stoped the injections at 20wks so did not have to contemplate the issue, but I do understand that it is an added stress. In the end I had to have an emergecy c-section while still on asprin (at 37wks 4 days). The anetatist (sp) went through the extra risk of having a spinal block for the c-section due to the higher prob of bleeding into the space that they put the injection because of the asprin, vs going under a general (which still has a slightly higher risk of complications due to the asprin) and gave me a choice of what I wanted to do...I wish I had been able to/thought to/pushed to have the conversation with my ob/an anetatist when not stressed about my baby and after a few hours of unproductive labour! In the end (eg after 30 secs of thinking) I had the spinal and the emergency c-section and all went well. I hope that makes sense

Hope that your placenta moves and you dont need an emergency c-section, but also push your ob to have the 'what if' conversation if you need to!

Good luck.
FG