Wife Returning to Work after Baby is Born

My wife decided that she wanted to return to work even though we really don't need the extra money right now and I am just not happy about it.  I could understand if we needed the money or if she got a job working a few hours a week but returning to a full time job is just plain insane, in my opinion. 

I know that taking care of a baby and a husband is like having 2 full time jobs and with my mother-in-law coming to stay with us I think it would work out better if both of them took turns watching after Baby Dumpling.  She can be a real handful sometimes so it works better if 2 people are doing it.   Sure we wouldn't need to pay for daycare or a babysitter so that works out if she returned to work.  I thought that she would miss the baby and not want to leave for many hours a day, but at this time she doesn't have the feeling of missing the baby.  I think it's in the best interest for my wife and Baby Dumpling to be with each other so my wife can continue teaching her sign language and all the other things that a young baby needs to learn.  Soon the baby will be sitting up on her own, then starting to crawl and start solid food.  I think it would be best if at least one parent was around to see to these things.  Then there's the interaction with others, this past month Baby Dumpling and my wife were going to a play group at the library and I think it would be very important for this to continue.  My mother-in-law won't be able to take the baby to these places.  I have been trying everything to convince my wife not to return to work and I admit that some of it hasn't been very nice.  I tried to explain, in not such a nice way, that she'll miss the baby and she won't get to see many "firsts" of the baby.  So far nothing I've said has changed her mind.  Maybe it's just one of those things that she's going to have to figure out for herself and no one will be able to tell her different.  Tonight was an example of why I want my wife to stay home.  Baby Dumpling had foamy poop and my wife thought something was wrong then the baby started crying for no apparent reason.  Not cold, not hungry possibly sleepy but she cried really loud for almost an hour then she fell asleep.  I went on the online and looked up foamy baby poop and found that this can be caused by the baby getting too much front end breast milk.  We are not sure how this can happen, nor are we sure why the baby cried so much, so loud for so long.  The good thing is Baby Dumpling will get her 4 month check up tomorrow so we'll be able to ask about it.  But this is one reason why I think my wife should become a full time mom.  She can watch for the changes with Baby Dumpling and that is useful information, not that my mother-in-law can't do it, but I would just feel better if my wife was in charge.  I have a few more days to try and convince my wife, but I'm running out of reasons.  If my wife want to feel like she's contributing to the household maybe I could teach her how to trade stocks, then she only works a few minutes a day because I'll do the research and she just has to put in the buy or sell orders.  In reality, my wife might need to return to work for more personal reasons that I don't understand yet.