Study Shows Marked Increase in Diagnosed Infertility Among Women Aged 35 to 49

Background: Egg Cells and Risk Factors

From around the age of 35, both the egg cell reserve and the quality of egg cells decline significantly. This reduces the probability of pregnancy. The success of a pregnancy is largely dependent on the age of the egg cell. Conditions such as endometriosis, polycystic ovary syndrome, metabolic disorders, and excess weight are also being diagnosed more frequently today and contribute to this risk.

Worldwide, around eight to twelve percent of couples experience fertility problems, according to the study. Women are overall more frequently affected than men.

Database and Country Comparison

The figures cited refer to the share of diagnosed infertility in the total population of 35- to 49-year-olds—and not to the biological infertility rate among women who currently wish to have children. The global average stands at 6,907 cases per 100,000 women, according to the data. Spain, at 2,226, is well below the global average, while Belgium, at 8,499 cases per 100,000 women, tops the European figures cited.

Viennese reproductive medicine specialist Beda Hartmann places the results in a more nuanced context. "The number of couples with unfulfilled desire for children has certainly risen, but that does not automatically mean that biological primary sterility in women has increased to the same extent." However, she expects interest in so-called social egg freezing—preventively freezing unfertilized egg cells—to grow in the coming years. "It would be advisable to freeze egg cells as early as age 25."

Criticism from Vienna

Eva Beaujouan, professor of demography at the University of Vienna, who was not involved in the study, voiced sharp criticism in remarks to the German Science Media Center. "It would be wrong to assume that the results show an increase in infertility among women who wish to have children." The study captures a population indicator, not an individual risk value. Nor can it confirm that the country differences reported in the international comparison actually exist.

Beaujouan doubts in particular the figures for Austria, which "appear far too high." Austria is neither a leader in late childbearing nor in the use of artificial insemination; the number of IVF treatments per woman lies in the European middle range, or rather below it. The methodology, and in particular the extrapolation, are also insufficiently described; "How precise the figures presented actually are can be assessed only with difficulty."

The Viennese demographer attributes the shift in family formation to longer periods of study, economic uncertainty, and youth unemployment. "People have children at a higher age due to longer periods of study, economic uncertainty, and youth unemployment." Factors such as higher life expectancy and changes in values and attitudes also play a role. "In addition, priority is given at younger ages to other activities such as career or travel."

Political Conclusions

As a political response, Beaujouan calls for reliable framework conditions. "A state must invest sufficiently in reliable childcare and a supportive infrastructure, so that every person who wants to have children can do so at the age they wish." The trend is unlikely to be reversed, "but perhaps stabilized." An earlier WHO evaluation for the period 1990 to 2021 found no marked increase in infertility prevalence worldwide.

The present finding is based on diagnoses, not on measured biological infertility, and is therefore of only limited informative value regarding the actual risk for women who wish to have children.

(Klaus Taschwer, 7.7.2026)