I'm posting this as an FYI anyone else has the same freak out moment as I had this morning in an effort to ease your mind. I had intercourse with my husband yesterday twice. It had been about a week since we had last done it. This morning, I woke to blood in my parties (close to 12 hours after intercourse), not just spotting, but blood. Being that this is my first pregnancy, I freaked out in a panic, called my doctor and got an US immediately. Everything turned out to be fine, strong HB of 176 and measured on schedule at 10w4d. I had never heard of this being an issue before, but apparently it's more common than I thought. Just thought I would share in case anyone else finds themselves in the same freaked out boat!