“In fact, 98 percent of Catholic women use birth control at some point in their lifetimes,” reported NPR on Feb. 10

“Studies have shown that 98 percent of Catholic women have used artificial contraception at some time in their lives,” said the New York Times the same day.

“Birth-control is widely used even by Catholics: 98 percent of American Catholic women have used contraception in their lifetimes,” the Washington Post said Feb. 12.

Ever since the battle erupted between Catholic bishops and the Obama administration over providing free contraception coverage as part of health plans for workers, a striking figure has appeared in the news – that 98 percent of Catholic women have used contraceptives.

The facts

The 98 percent figure first appeared in an April 2011 study written by Rachel K. Jones and Joerg Dreweke of the Guttmacher Institute, a non-profit organization that promotes reproductive health.

The study is titled “Countering Conventional Wisdom: New Evidence on Religion and Contraceptive Use.”

The study drew on data from the 2006-08 National Survey of Family Growth, which relied on in-person interviews with 7,356 women from the ages of 15 to 44.

But while the study says that 98 percent of “sexually experienced Catholic women” have “ever used a contraceptive method other than natural planning,” the data shown in the report do not back up that claim. In fact, a supplementary table in the report, on Page 8, even appears to undermine that statistic, since it shows that 11 percent of Catholic women were using no method at all. That has led to criticism of the statistic.

The Guttmacher Institute, citing “confusion” over the statistic, last week posted the data behind it.

It turns out it was based on a question that asked self-identified Catholic women who have had sex if they have ever used one of 12 methods of birth control. Jones, in an interview, said the women were asked to answer “yes” or “no” whether they had used each of the different forms; only 2 percent said they had used only natural family planning.

In other words, a woman may have had sex only once, or she may have had a partner who used a condom only once, and then she would be placed in the 98 percent category. Jones said the correct way to describe the results of the research is this:

“Data shows that 98 percent of sexually experienced women of child-bearing age and who identify themselves as Catholic have used a method of contraception other than natural family planning at some point in their lives.”

As she pointed out, “In social science circles, sexually active means you had sex recently. Sexually experienced means you’ve had sex at least once.”

The data listed in the Guttmacher report, meanwhile, referred to current contraceptive use among “sexually active women who are not pregnant, post-partum or trying to get pregnant.” That is a smaller universe of women, and it shows that 68 percent of Catholic women used what are termed “highly effective methods”: 32 percent sterilization; 31 percent pill; 5 percent IUD.