Jessica Simpson thinks it will be ''like a fire hydrant'' when her water breaks.

The 31-year-old star - who is expecting her first child with fiance Eric Johnson - joked that she feels as though her bump, which still has four weeks to go until it reaches full term, is the size of a ''bowling ball'', and explained she is so big because she has a lot of amniotic fluid surrounding her unborn baby.

She said: ''I feel like I have a bowling ball sitting on my hoo-ha!

''Apparently I have a lot of amniotic fluid, so whenever my water breaks it will be like a fire hydrant!''

While she and NFL star Eric have temporarily put their wedding plans on hold as they prepare for impending parenthood, Jessica explained she already sees the 32-year-old sportsman - who she has been in a relationship with since May 2010 - as her ''husband'' but they are just conducting their relationship ''a little bit backwards''.

Speaking as part of an interview on 'Jimmy Kimmel LIVE!' last night (19.03.12), she said: ''Eric feels like my husband already, we are just doing it a little bit backwards.

''We met at my house - he just came with one of my friends to my house, we were watching March Madness or something. He came over and we sat on my stairwell and talked and I just haven't let him leave!''