The size of a brood is also important. Using the 2018 General Social Survey collected by NORC at the University of Chicago, I statistically modeled mothers’ reported happiness against the number of children they have, and found that well-being increases as a woman has her first, second, and third child. The fourth child and beyond are associated with falling happiness. (To be precise, the optimal happiness point occurs at 3.14 kids, but getting that .14 of a child is a bit tricky.) The aspects of motherhood that lower happiness are obvious and specific, from meltdowns in the supermarket to calls from the principal’s office. The benefits to well-being are more diffuse, and centered on a sense of purpose and meaning. As one team of scholars summarizes the evidence, “When compared with nonparents, parents with children in the home have low levels of affective well-being … and high levels of life-meaning.” Logically, then, a mother’s overall well-being should rise as kids grow up, because the pressures of raising young kids decrease, while the sense of meaning that adult children bring their mothers stays high. But the opposite appears to be true. In 2016, three social scientists looked at the life satisfaction of women with and without kids. They found that during childbearing years, mothers and mothers-to-be were happier than non-mothers. However, by age 40 and beyond, mothers’ life-satisfaction levels were generally a bit lower than their childless counterparts.