what is the 'line'?

can anyone tell me what the brown line is for? the one running straight down my big belly?

every time i go to the doctor i forget to ask.

It's not really 'for' anything. It's called a linea nigra. It's the darkening of your linea alba- a line that you always have down the middle of your belly but just can't see. THe hormones of pregnancy act on the melanin (pigment) producing cells of your skin and cause them to make more pigmentation. This is just one spot that often gets dark- usually your areola get dark too and sometimes women also get spots on their face. Everything usually goes back to normal afterwards.

I don't have a linea nigra yet, but I do have a fine but kind of dark line of hair running above my belly button up towards my chest. Go figure!

Mine started as the hair line, now it's a DARK brown line from my lower belly way up almost to my chest!