What do readers take away from this? One might think that nearly half of households in the United States are childless. This statistic simply makes no sense!
To be fair, the choice of the 15–44 age range is a sensible one: it corresponds fairly closely to women's childbearing years. The number of women who have children outside this range is quite small. But we shouldn't forget that some women will never have children. In France, this is the case for 10% of those born in 1940. This percentage is rising and will likely be around 15% for those born in 1980. Lastly, one more statistic worth keeping in mind: in France today, the average age of women having their first child is 28, and the average age of women giving birth is 30.
Let's now run a simple simulation: consider a theoretical population of women of different ages, from 15 to 44, with each age group having the same number of members (assume zero mortality over these thirty years). Suppose that 50% of women give birth to their first child at 25, that 10% never have a child, and that the remaining 40% give birth to their first child at 30. Then, in this theoretical population,
