I had one with my twins, it was there at 8 weeks, my OB recommended no sex and plenty of rest. They did a recheck at 12 weeks to see if it went away yet, it hadnt, but it was barely there. By 16 weeks at my next ultrasound it was gone. Most of them go away on their own, just get as much rest as you can and from experience your body will let you know if you need to slow down. Hope this is helpful!