Having done the baby thing twice (though on land) it doesn't seem like that big a deal having a infant/baby on a boat. Perhaps outside some emergencies. The real problem starts around 1 year old, to perhaps 3-4! A toddler than can crawl, then run, jump, climb. And is incredibly stubborn and challenging limits/parents at every turn, for inexplicable reasons (my daughter love cookies, but say no to them if offered, because default is always "no!"). I know people have, but I would not want to do that. And as with everything one was easy, 2nd exponentially worse..
Here I have to disagree with you.
We took a three day old aboard and she grew up doing a circumnavigation under sail and a couple of TransAts and some really interesting side trips up the Orinoco and Amazon rives as well.
She grew up to be a pretty cool person.
Whereas you have everything from "stranger danger' to terrorists, crazies and vehicular traffic, (to mention just a few of the dangers your children face every day) to shield your child from, we had only ONE
STAY ON BOARD
. Nothing else. No colds or flue from the other kids in school, no broken bones or psyche over sports, etc.
It may actually be a very safe and healthy way to raise a child if you consider how nuts it is to live in society, such as it is, these days.