Is it possible?

I'm training for a marathon in April. I'm 5 weeks into my formal training program and LOVING it. I ran into a hiccup last week though. After 12 years of marriage I am pregnant for the first time. SURPRISE, SURPRISE!! We adopted our babies I have been fulfilled as a mother for the past 4.5 years. Pregnancy was once a hope and wish, but has been furthest from my mind in recent years. I cannot even explain the shock in finding out I'm pg. I have never been pregnant. We did months and months of fertility and an IVF cycle in 2000. None of which were ever successful, yet, no explination had been given for our infertility. This past fall I started my "pre-training" in anticipation of accomplishing my marathon that had been on my "list" for about 3 years. I couldn't even run 5 minutes when I started. But I kept working my way up and by the week of Christmas I was ready to start my formal training program for my marathon in April. Little did I know, I was already a few days pregnant. I missed my period early this month and thought, "well, I'm running more than ever b/f in my life, surely it's that." But last week after a couple bouts of nausea, I got a pg test and it was positive. So now I'm trying to figure out how far I'm going to take this training. Can I run my marathon at 4 months pg? I don't know. Should I add mileage? I don't know. I'm going to keep running and training for now. It's still early, and I'm not sure how all of this is going to pan out.