A new nationally representative study of young adults aged 18–29 in the United States finds that 19% of women and 13% of men—corresponding to 3.2 million women and 2.6 million men—believe they are likely to be infertile, according to “Missed Conceptions or Misconceptions: Perceived Infertility Among Unmarried Young Adults in the United States,” by Chelsea Bernhardt Polis and Laurie Schwab Zabin, of Johns Hopkins Bloomberg School of Public Health. Yet only 6% of married women aged 15–29 in the United States are actually likely to be infertile.

The authors found that perceived infertility among men was linked to men’s belief that they are likely to have sex in the near future without using contraceptives. However, contrary to findings from other studies, Polis and Zabin did not find an association between perceived infertility and recent nonuse of contraceptives—perhaps, they suggest, because their sample was too small. They do note that the possibility of such an association merits further study in a larger sample, because individuals who do not think they can get pregnant may be less motivated than others to use contraceptives, and unless they are actually infertile, they may have an elevated risk of unintended pregnancy.

Polis and Zabin point out that some public health messages designed to encourage consistent contraceptive use focus on the fact that pregnancy can occur after a single act of unprotected intercourse and do not adequately explain the probability of pregnancy. Polis and Zabin raise the concern that an oversimplified message may inadvertently lead some individuals to assume they are infertile if pregnancy does not occur after one or several acts of unprotected sex, and may result in reduced motivation to use contraceptives.

A recently released study from the Centers for Disease Control and Prevention reported similar findings among 15–19-year-olds whose unintended pregnancies led to a birth. An analysis of data from the 2004–2008 Pregnancy Risk Assessment Monitoring System found that half of these teens had not been using any method of birth control when they got pregnant. And nearly one-third of young mothers who had been nonusers had believed that they could not get pregnant.

Missed Conceptions or Misconceptions: Perceived Infertility Among Unmarried Young Adults in the United States” is currently available online and will appear in the March 2012 issue of Perspectives on Sexual and Reproductive Health.