COLUMBUS, Ohio - A national study suggests that a significantly greater number of highly educated women in their late 30s and 40s are deciding to have children - a dramatic turnaround from recent history.
Among college-educated women, childlessness peaked in the late 1990s, when about 30 percent had no children, according to the new analysis of U.S. data. But childlessness declined about 5 percentage points between 1998 and 2008.
"We may be seeing the beginning of a new trend," said Bruce Weinberg, co-author of the study and professor of economics at Ohio State University.
"One of the major economic stories of the second half of the 20th century was that highly educated women were working more and having fewer children. It is too early to definitively say that trend is over, but there is no doubt we have seen fertility rise among older, highly educated women."
The turnaround in fertility is especially surprising because other trends - particularly lower rates of marriage - would tend to keep fewer women from becoming mothers.
The study shows that college-graduate women born in the late 1950s were the turning point. They were less likely to have children than previous cohorts up until their late 30s, when they reversed the trend and showed large increases in fertility.
Highly educated women born since then have continued the trend, being more likely to have children, and starting to have children at earlier ages.
It is not clear from this research whether older, highly educated women are dropping out of the labor market to have children, or are continuing to work.
"We don't have the data in this study to say whether they are opting out of the labor market. But we can say they are increasingly opting for families," Weinberg said.
The first author on the study is Qingyan Shang, an assistant professor at the University at Buffalo, State University of New York. Their study appears online in the Journal of Population Economics, and will be published in a future print edition.
This study is a considerably more comprehensive analysis of highly educated women's fertility than several other recent studies of the subject that came to contradictory results, according to the authors.
The researchers used two major data sets: the June Current Population Survey for 1980 to 2008, which is a joint effort between the U.S. Bureau of Labor Statistics and the Census Bureau; and the Vital Statistics Birth Data from the National Center for Health Statistics.
Findings on women's fertility were very different depending on education level, Weinberg said.
"For the less educated women, it is more a story about the timing of their fertility. They are having their children earlier now than they used to, but they are not having any more children overall," he said.
"For the highly educated women born after the late 50s, they are more likely to have children than did previous cohorts, and they are having them near the end of their childbearing years."
For women with graduate education, cumulative fertility is flat among 25-29 year olds in recent years. It increases somewhat among 30-34 year olds and considerably more among older women.
The results for women with bachelor's degrees (and no advanced degrees) are not as dramatic. There are no discernible trends for women aged 25 to 34, but there are increases at older ages. For women who have some college, but did not graduate, cumulative fertility increases at all ages, with the increase starting earlier at younger ages.
The study notes that one possible reason that women in their late 30s and 40s are now deciding to have children could be that fertility treatments have become more accessible and affordable in recent years.
With the data available, there is no completely accurate way to calculate how many older women are using fertility treatments. But one way to make a rough estimate is to see how many women are having multiple births - more than one baby at a time. That's because fertility treatments are known to be associated with high rates of multiple births.
In their analysis, the researchers found that multiple birth rates began increasing around 1990 - especially among highly educated older women, who would probably be most likely to be using fertility treatments.
Among college-graduate women in their early 40s, the multiple birth rate more than tripled from 1990 to 2006.
That suggests the use of fertility treatments played a role in the increasing number of educated older women having children. But it is not the only cause, according to the researchers.
"Although our estimates are not exact, it is clear that there was an increase in older women having children even after taking into account the fact that fertility treatments are more accessible and affordable," Weinberg said.
"Fertility treatments contributed, but it isn't the only factor."