I'm sure that some people are able to make it work, but in general the answer is: you don't. Taking care of a baby is a full time job in and of itself, associated with frequent interruptions and sleep deprivation.
People do it all the time. We did it. In our industry, in two-tech-worker families, there's a norm of staggered parental leave. Contrary to a lot of popular opinion, taking care of an infants or toddler isn't a full time job. In fact, even if you're especially attentive, there are long, long stretches of downtime.
I'm as pro-natal as they come, but a newborn should have your full undivided attention.