In a recent study published in Fertility and Sterility, researchers estimated the changes in infertility in the United States (US) from 1995 to 2019.
Infertility is typically the inability to conceive after a year (or longer) of regular, unprotected intercourse. Although reports suggest a decrease in the infertility rate in the US, it remains a significant concern. Globally, around 8% to 12% of couples are affected by infertility.
Studies have observed increased rates of sexually transmitted infections (STIs) since 2007, whereas the rate of pelvic inflammatory disease (PID) has declined. Moreover, access to reproductive health services remains unattainable for many women.
About the study
In the current study, researchers examined the trends in infertility for the 1995 – 2019 timeline in the US. They used data from the National Survey for Family Growth (NSFG), collected by the National Center for Health Statistics (NCHS). NSFG is a stratified multi-stage national probability sample of males and females aged 15 – 44 in the US and collects data on sexual and reproductive health. Data from the 1995, 2002, 2006-10, 2011-13, 2013-15, 2015-17, and 2017-19 cycles were used.
Using data from these survey administrations, a pooled sample of married or cohabiting women was generated. The team relied on NSFG-defined measures of infertility, namely, a woman who did not conceive after 12 months of regular unprotected intercourse with her husband or cohabiting male counterpart. The (independent) variables were age, ethnicity, race, education, parity, PID treatment, income, survey year, and ‘in-care.’ The in-care variable was introduced to capture information on whether women received sexual and reproductive health services during the survey year.
Although an imperfect measure of access to sexual and reproductive health care, the in-care variable could estimate who received regular sexual/reproductive health care. They performed bi- and multivariable logistic regression models to investigate the association between independent variables and the odds of infertility among the study subjects.
The age distribution was relatively stable during this period (1995 - 2019), unlike in previous work (1982 – 2002) by different authors where the ‘baby boom generation’ prevailed. Women continued to pursue higher education during this period; however, the number of women with lower incomes increased in this timeframe. Racial and ethnic distributions were also relatively constant, with a greater representation of minority women.
More people accessed sexual and reproductive health services, with the number of women increasing over the (survey) years. The proportion of married and cohabiting women with infertility per cycle was estimated. The infertility trends generally declined, followed by slight gains over time. In 1995, 6.9% of married and cohabiting individuals were infertile.
In the subsequent survey iterations, the percentages of infertile subjects were 7% (2002), 5.8% (2006-10), 6.3% (2011-13), 7% (2013-15), and 7.2% (2015-17), and 8.1% (2017-19). Notably, a sharp increase in infertility with age was evident among nulliparous women. The authors noted that the computed changes/trends in infertility over the survey years were not statistically significant.
The odds of infertility increased with age for nulliparous and parous women. This was particularly pronounced for nulliparous women aged 40 – 44, who had approximately 11 times greater odds of being infertile than those in the reference group. Women with higher education levels showed lower odds of infertility than those who did not finish high school.
Women in the middle-income categories also had lower odds of being infertile than women with lower incomes. Statistically significant higher infertility rates were noted among non-Hispanic Black women. However, the infertility rates were not significantly different among non-Hispanic white women, Hispanic women, and non-Hispanics of other races. Also, In-care women showed significantly lower odds of infertility.
The findings showed that estimates of infertility, with a lower rate (5.8 %) during the 2006-10 survey cycle and higher (8.1 %) during 2017-19, were not statistically significant. This observation applied to almost every sub-group studied. Nevertheless, the multivariable model revealed higher odds of being infertile in women who were older and nulliparous and among those with lower education, income, or non-Hispanic black ethnicity.
In conclusion, the study noted that, in contrast to previous research, infertility in the US was not declining, and demonstrated that age, education, income, parity, and race were associated with infertility. It also highlighted the significant contribution of having access to sexual and reproductive health services in managing infertility.