New estimate for unwanted births

Women around the world are experiencing more unwanted pregnancies than previous research had suggested, Ohio State University professor John Casterline said yesterday during a lecture in Wallace Hall.

Casterline, who heads Ohio State's sociology department, said current statistics underestimate the global rate of unwanted fertility. He addressed an audience comprised of roughly 40 graduate students and postdoctoral researchers who participated in the Notestein weekly seminar series offered by Princeton's Office of Population Research (OPR).

Casterline's presentation, entitled "The Estimation of Unwanted Fertilty," discussed existing methods by which demographics experts calculate the percentage of unwanted births within given populations of sexually active women. He then went on to introduce a new approach to unwanted fertility estimation.

This new method, labeled by Casterline as an "aggregate prospective estimator," is designed to track cohorts of women over time between two rounds of surveying. The surveys track the dates of recent births reported in the second survey and compare these actual birth incidences to the prospective birth incidences collected in the first survey, which asks women of childbearing age whether or not they want or intend to have another child.

Casterline called his new approach "embarrassingly simple," and went on to discuss some of the possible errors associated with his aggregate estimator. The incidence of random response error was minimal in most cases, and even a shift in women's family planning preferences over time was a trivial impediment to the new approach, he argued.

Casterline also outlined the implications of the new method through a series of statistical graphs. He compared the demographic data obtained with the aggregate estimator to the data obtained with the standard method used by the Demographics and Health Survey, which directly and simultaneously relates a woman's ideal number of children to the number of existing children. "Our estimate," Casterline said, "suggests there is even more unwanted fertility than implied by current statistics."

The audience was critical yet enthusiastic toward Casterline's proposal. Many of those who voiced concerns during the discussion suggested that the next step in Casterline's research should be to further narrow the samples of women surveyed so as to see whether region, age or income-related factors would affect the reliability of the aggregate estimator.

Following the formal seminar discussion, Casterline discussed the implications of his findings in a more relaxed setting, commenting that the main message of his data was that societies around the world are still a long way away from fulfilling the mantra of "every child, a wanted child." He admitted that perhaps this utopian ideal was unattainable but agreed that it was nevertheless worth striving for.

Casterline has worked at various other research institutions before Ohio State, including the sociology departments at Penn State and Brown as well as the World Fertility Center in London.

His research has dealt mainly with the dynamics of social networks and changes in fertility rates over time. He has focused his attention on Arab, Latin American and West African countries.