Sometimes it may be a concern. It can possibly mean tjat bub is growth restricted. But it can also mean nothing and that bub will catch up or that the ultrasound may have been off a little. They should monitor you closely over the next few weeks to see. Even if bub is growth restricted, dont be concerned its less worrying than it sounds. My lo was and was born perfectly fine, just on the small side. Best of luck
Don't worry bout it they told me I was measuring 4 weeks ahead when I went to growth scan he was ryt on track just sometimes how the na by is lying at the time can give different mesurments also different doctors will get different readings x
I personally haven't experience this, but I will prayer everything goes well in your pregnancy. Good luck!