N.M.
Like a previous post said, make sure that you really want to stay home and can do it financially. Obviously before you had the baby, you planned to return to work since you took maternity leave instead of resigning. So my question is - are you sure you want to stay home?? Or are you just going through the transition of returning to work?? Because I have been there and it's hell. Leaving your first child in the arms of someone else while you go to work is painful and difficult, especially when your hormones are still raging. But I will tell you - it gets better!!! And especially if you LIKE your job and the people you work with. That makes all the difference!! If you stick it out, you will eventually get into the swing of things and you might enjoy it. I know working makes me a better mother than if I were home all day with my son. That is just me, it's different for every mother (whether you can do the stay-at-home thing). Also keep in mind that it's easier to work with just one child and you can always stay home after your 2nd.
If you are determined to quit, that also gives you the advantage to make some requests because you have nothing to lose. Can you work part-time in your position? Can you telecommute? It wouldn't hurt to ask since the worst they could say is 'no'. Good luck with your decision!!