While it is still too early to be certain, research clearly shows fertility rising for older, highly educated women since the 1990s. (Fertility is defined as the number of children a woman has had.) Childlessness also declined by roughly 5 percentage points between 1998 and 2008. “Women born in the late 1950s are the turning point,” says Qingyan Shang, assistant professor of economics at the University at Buffalo. Members of this group initially showed low fertility. But fertility increased for them when they reached their late 30s and early 40s. The paper, co-authored by Bruce A. Weinberg, professor of economics at Ohio State University, appears online in the Journal of Population Economics and will be published in a forthcoming print edition. Two previous studies which examined fertility among highly educated women had limitations and came to conflicting conclusions, Shang says. One focused only on women in their late 20s and another examined fertility for women in managerial positions. Using a sample of professional women makes the results difficult to interpret because women who have more children may switch to other occupations, Shang says. “We did a more comprehensive study. We instead define the sample using education, which is less responsive to short-term fertility decisions.” The conclusions are derived from data gathered by the June Current Population Survey, compiled by the U.S. Bureau of Labor Statistics and U.S. Census Bureau. The researchers also used the Vital Statistics Birth Data from the National Center for Health Statistics as a second data set. The research did not directly address what factors might be contributing to the fertility increase.  “We did list some possible explanations based on previous research,” says Shang, including the idea of “the learning story,” in which decisions of previous generations inform later decisions by subsequent generations. There has also been an increased supply of personal services that have reduced childcare expenses. Other research shows men may be taking more responsibility for child care. Whether women are choosing families instead of or in addition to their careers is unclear, Shang says. “We know these women are opting for families. We don’t know if they in turn are opting out of the labor market.” The study also indicated an increase in multiple birth rates around 1990, suggesting fertility treatments may have played a role. “The data does not include information about whether women used fertility treatment,” Shang says. “But we use the trends in plural birth rates to impute the share of the increase in fertility among highly educated women that is attributed to fertility treatment.”