The last thing I need is to have my sleep interrupted by kicks and squirms. But to be so close to my children, at the one time of day when they are too bleary to fight with each other, is priceless to me.

When I was 32, three years into my blessedly peaceful second marriage, 16 months into the motherhood gig, five months pregnant with our second child, I sat on the floor of our New York apartment in stunned silence.