Catholic women overwhelmingly use birth control, despite an official ban by the church, a new study finds.

The study, conducted by reproductive health institute Guttmacher, finds that 98 percent of sexually active Catholic women use or have used birth control other than church-approved natural family planning. Only 2 percent of Catholic women have used natural family planning, which involves tracking the menstrual cycle to avoid sex during fertile periods.

“In real-life America, contraceptive use and strong religious beliefs are highly compatible,” Rachel Jones, the report’s lead author, said in a statement. “Most sexually active women who do not want to become pregnant practice contraception and most use highly effective methods like sterilization, the pill, or the IUD. This is true for Evangelicals and mainline Protestants, and it is true for Catholics, despite the Catholic hierarchy’s strenuous opposition to contraception.” [Read: New Surprising Results on Abortion and Religiosity]

The analysis is based on a nationally representative U.S. government survey, the National Survey of Family Growth. Overall, the survey found that 99 percent of women have used birth control, and almost all of of those who don't want to get pregnant use some method of contraception. Eighty-nine percent of Catholic women, 90 percent of mainline Protestants and 91 percent of Evangelicals who are not currently trying to conceive use birth control, Jones and her colleagues reported.

About 68 percent of Catholic women use a highly effective method of birth control, meaning hormonal methods, the IUD or sterilization, compared with 73 percent of mainline Protestants and 74 percent of Evangelicals. More than 40 percent of Evangelicals use male or female sterilization as birth control, outpacing other religious groups by about 6 percent to 9 percent.

Even Catholic women who attend services more than once a month use natural family planning at a rate of only 2 percent, the researchers found.

The study also found that regardless of religion, at least 75 percent of women are sexually active by their early 20s, whether they're married or not. That number was 75 percent for Evangelicals, 86 percent for mainline Protestants, 89 percent for Catholic women, and 79 percent for women as a whole.

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