I'll line-item as much as I can for the one child we currently have, aged 15 months.
Utilities: ~$20/month for a 1000 sq. ft. apartment, low COL
Baby was born in the fall, and since little babies can't regulate their body temperature like adults can, and since it's not safe for them to sleep with blankets, we had to keep the temperature warmer all winter than we would have normally.
Housing: 0
We gave up having office space at home and now the 2nd bedroom is a bedroom. Since about 1/3 of DH's job is from home, this has been difficult, and now a 3br is our minimum requirement next time we move.
Saving: 400/mo, YMMV
^College savings, as desired
Food: 40/mo?
Of course this starts out nearly free if breastfeeding (~75/mo for formula if not) and gradually increases as you add solids. Baby eats a lot of yogurt, frozen veggies, fruit, eggs, and beans. I don't know how to quantify our convenience foods, but we did shift to eating more at home so that we could eat during Baby's naptimes.
Diapers, other: 60/mo
We use disposables, cloth was too much work for me, personally, though I know many, many people do it gladly. Grandparents have currently gifted all of the baby clothes we have needed and I was able to borrow infant gear from a friend (swing, stroller, crib). These things can easily be found used, as well. Car seats can be an expensive one-time cost.
Medical: YMMV, greatly.
Ours is 0 because of our insurance plus a reimbursement program through work.