I went back to work full-time when Zoe was 3 months old. Finances would have allowed me to stay home with her but I went back by choice, my career is important to me too. I could never be a SAHM, I'm a psychologist and I love my job.
This time around I will be going back to work 4 days a week when Alex is 3 months old also.
We don't put them in daycare though, MIL looks after them while DH and I are at work. It gives me peace of mind at least, that they are with someone I trust.
