Worse still, the fertility gap itself may be related to the phenomenon called “the paradox of declining female happiness.” In a 2009 paper, labor economists Betsy Stevenson and Justin Wolfers documented that subjective measures of women’s happiness have been declining since 1970, both absolutely, and also relative to men.47 The scholars stated that “this decline in relative well-being is found across various datasets, measures of subjective well-being, demographic groups, and industrialized countries.”48