Jonathan Last's new book, "What to Expect When No One's Expecting," is generating a great deal of commentary on both the Left and Right, most of it about the economic costs of a society with fewer children and smaller families. Family size has been declining dramatically in the Western world for decades. The past 20 years alone have seen the number of one-child families double as men and women wait longer to have children, and more infertility issues arise. Little has been mentioned of the social or emotional costs to a culture of such a decline.

Child-rearing does not make personal economic sense if you believe the outlandish contemporary estimates of the costs. But these estimates often ignore economies of scale -- the common-sense reality of hand-me-downs, shared toys, and the fact that parents do not necessarily have to pay the entirety of a child's college tuition. Moreover, from a cultural perspective, kids in larger families offer an enormous social good.

From the moment a child is born into a family with multiple siblings, he/she quickly learns and adapts to the fact that he/she is not the center of the universe. School teachers and parents of families of any size try to teach children the importance of sharing, taking turns and working as a group, but kids with many siblings learn these things naturally in the home as a matter of survival. Daily life is the lesson. If they do not share the toys in their house, they are not going to be able to play that day.

These children also learn quickly know how to entertain themselves. As children, my four siblings and I never lacked for games or imaginative and creative play because we had each other to play with. I have never met a child from a large family who wished their parents did not have so many kids. I have met many an only child, though, who pined for a sibling or siblings when they were growing up, struggling with the reality of both loneliness and boredom. As Beth Salamon poignantly writes in a New York Times piece titled "Still Lonely in a World With More 'Onlies,' " "It isn't a bad life. But it is a sad life sometimes, missing what was never there. In kindergarten we had to draw our families. As I watched the others filling in crayoned brothers and sisters, my family suddenly seemed wrong, so I drew a brother and named him Doug."

Are large families oppressive to women, as all those demeaning and misogynistic references to "barefoot and pregnant" always suggest? (When did it become OK to refer to a woman's pregnant state as some sort of mark of inferiority?) A study last year by researchers at the University of California, Stanford University and the University of British Columbia in Vancouver actually found parents "report relatively higher levels of happiness, positive emotion and meaning in life" than nonparents. Parenthood is not a prison for women. For countless mothers of many children, it is a source of joy.

The joy of parenthood is probably best expressed in the words of Mother Teresa: "How can you say there are too many children in the world? That's like saying there are too many flowers."

Elise Ehrhard is a freelance writer living in Northern Virginia.