US infertility rate plateaus

"These findings suggest we have to continue to invest in our public health services and push for equal access to reproductive and sexual health care if we want to meet national goals of reducing infertility," says Johns Hopkins University School of Medicine medical student Morgan Snow, who is the study's first author.

Infertility -- defined as the inability to achieve a pregnancy after at least a year of unprotected sex -- affects millions of men and women of reproductive age. Studies conducted in the early 2000s found that rates of infertility declined throughout the 1980s and 1990s, although reasons for the decline were unclear.

More recently, experts suspect that rates of sexually transmitted infections, which have consistently risen from year to year, are contributing to the rise in the infertility rate. In addition, they say, the number of women receiving preventive gynecologic care has dropped and the average age of first-time mothers has risen.

"This is a unique time period where sexually transmitted infections are on the rise and there are a number of emerging threats to health care access," says Maria Trent, M.D., M.P.H., Bloomberg Professor of American Health and Pediatrics at the Johns Hopkins University schools of public health and medicine, and senior author of the research report. "For care providers who are working with women, it's important to understand how these factors might be influencing fertility."

For the new study, Snow and Trent analyzed data on 53,764 women who participated in the federally supported National Survey of Family Growth (NSFG). While the survey did not ask explicitly about infertility, it contained questions about sexual activity, contraception and pregnancy that were not used in previous studies to estimate infertility rates. It also collected information about sociodemographic and health care factors.

Based on the responses, the researchers concluded that the rate of infertility varied slightly from year to year, with a low from 2006 to 2010 of 5.8% and a high between 2017 to 2019 of 8.1%. However, these fluctuations are not considered statistically significant, and the team concluded that overall fertility rates did not significantly change during the study period.

In particular populations, however, infertility rates were significantly higher than average, compared with the general population. Women age 40 to 44 were about 11 times more likely to be infertile than younger women, women who did not complete high school were twice as likely to be infertile as those with higher levels of education, non-Hispanic Black women were 44% more likely to be infertile than women of other races and women who had not recently received sexual health care were 61% more likely to be infertile. Unlike previous studies, the new data did not show a higher rate of infertility for Hispanic women.

"These numbers tell us that fertility is still a problem, particularly for certain vulnerable populations," says Trent, who is also the director of the Division of Adolescent/Young Adult Medicine at Johns Hopkins Children's Center.

Understanding who is at highest risk of infertility can help shape public health guidelines and messaging, Trent notes. The association between preventive health care access and infertility, for example, suggests that emphasis on identifying and treating sexually transmitted infections may reduce infertility by reducing rates of pelvic inflammatory disease, which is a major risk factor for infertility.

The researchers caution that their study was limited by its reliance on questions included in the NSFG, which were not designed to directly measure infertility rates or access to care. However, the study offers a valuable comparison with previous studies on infertility rates, Snow says. More work is needed to understand the complex sociodemographic factors behind the associations.

In addition to Snow and Trent, authors of the Fertility and Sterility paper are Jamie Perin, Ph.D., of The Johns Hopkins University, and Tyler Vranich, M.S., a former Johns Hopkins University student who is now a student at the Medical University of South Carolina. The research was supported by the National Institute of Nursing Research (NINR-R01NR013507 -- Trent).