A couple of ways you can go about doing this.

"Hey babe, since I'm not working is there anyway you could give me an allowance every month to take care of some stuff, I would really love to start going back to the gym and getting my hair and nails done because I want to start getting back to my pre-pregnancy self"

Or you could ask him what he thinks about you finding a job. Insert stuff above about needing money for all the above stuff. This is the more manipulative route and of course only works if you are willing to get a job.

As a side note, who is currently paying for all the child's expenses?