brown line

I got Brown line down belly botton for my first pregnancy. Now its about 4 yrs.. i don really remember whthr it went off or not. Did not notice. Now i doubt i m preg as i am late for 2 days. During shower i saw i hav that line. I am not sure wthr its the old one or new. If i had got it for pregnancy will it go off or can it remain for this long?