You have to have at least two kids for that, and with a big enough age difference for it to work.
And if it goes wrong you can get prosecuted for that and/or dragged through public infamy. In fact even if it doesn't go wrong you can probably still be reported for it.
Which is presumably a very good thing for child safety, but obviously there are these downstream effects.
Another similar thought was the theory that car seat laws act to cap more families at two children because with three, you can't legally fit both parents and the children into a normal car.
