I had two children during residency. One at the end of second year/beginning of third year and the second halfway through fourth year. I cannot imagine how difficult it would be to have an infant at home during the first two years. It is so hard to leave a baby overnight, especially if you are nursing. Plus, new babies and intern year are both incredibly stressful on their own. I think you would have to be kind of nuts to combine them on purpose.
Childcare is difficult during residency. Daycare hours do not typically correspond with intern hours, and nannies are expensive. Of course, if your husband has flexible hours or makes a lot of money, or you have family around, this may not be as big of an issue for you as it was for me (my husband was also a resident at the time).
If you have any questions, PM me.
Also, take a look at this forum: mommd.com