Reacción a "A study warns of a global rise in infertility among women over the age of 35"

The study by Yuanyuan Du et al. provides a comprehensive analysis of trends in infertility between 1990 and 2023 among women aged 35 to 49, assessing temporal trends, quantifying regional inequalities, identifying the main associated factors, and determining which countries have the greatest potential for improvement through the analysis of 204 territories within the framework of the Global Burden of Disease (GBD). According to their findings, in 2023 approximately 53.6 million women in this age group were affected by infertility, and projections estimate that this figure could reach 79.6 million by 2036.

The authors highlight that this group of women has received limited attention in epidemiological studies on infertility, despite accounting for a significant proportion of the global burden of disease. However, focusing the analysis exclusively on women aged 35 to 49 introduces certain biases that must be taken into account. Firstly, it is to be expected that this group would have the highest rates of infertility, given that from the age of 35 onwards there is a progressive decline in both ovarian reserve and oocyte quality, with a significant acceleration from the age of 40. Furthermore, the inclusion of women aged between 45 and 49, for whom the probability of spontaneous pregnancy is extremely low, may contribute to an artificial increase in the overall estimate of infertility associated with this age group.

Secondly, although the authors highlight the scarcity of specific studies on fertility in women of advanced maternal age, there are numerous studies that have addressed this issue from a clinical perspective. In this regard, recent studies have demonstrated a progressive decline in reproductive outcomes with age. For example, a study published by Sebastián-León in 2025 describes an annual decline of approximately 4.2 per cent in the embryo implantation rate in women over 40, highlighting the impact of reproductive ageing on the outcomes of assisted reproductive technologies.

The study’s main contribution lies in the scope of its international analysis, which enables the assessment of differences across 204 countries and the establishment of future projections regarding the trend in infertility. However, another potential methodological bias must be taken into account: the public health burden of morbidity represented by the proportion of women aged between 35 and 49 affected by infertility (defined according to the GBD as women of childbearing age who are trying to conceive but are unable to become pregnant). This indicator may be influenced by socio-economic and cultural factors, as well as factors relating to access to the healthcare system; furthermore, it disproportionately reflects the situation of older women, who face the greatest difficulty in conceiving.

The study highlights that, although historical differences between low- and high-income regions have narrowed, the burden of infertility is gradually shifting towards higher-income countries. In these contexts, women are more likely to delay motherhood and to access diagnostic tests and fertility treatments. The authors interpret this phenomenon as a consequence of broader social and economic changes, including the postponement of family planning until later in life and greater availability of reproductive services in certain developed settings.

In Spain, as in other developed countries, a significant increase in infertility has been observed among older women. However, it is important to interpret these data with caution: the increase observed in this age group does not necessarily imply an intrinsic rise in infertility, but rather reflects, to a large extent, a progressive delay in the age at first pregnancy driven by social, economic and occupational factors. Consequently, analysing this age group alone may confuse the effect of reproductive ageing with a supposed change in the population’s reproductive capacity.

The authors highlight the urgent need to develop more inclusive reproductive health strategies and to integrate infertility into national and international health agendas. Proposed measures include expanding public coverage of assisted reproductive technologies, investing in technological innovation, promoting informed family planning, strengthening health systems and enhancing international cooperation to ensure equitable access to reproductive care.

However, the rise in infertility associated with this age group cannot be addressed solely by expanding the range of assisted reproductive therapy options. Although these techniques are a vital tool for many patients, they do not address the structural cause of the problem. In countries such as Spain, it is also necessary to address the social factors that contribute to delayed motherhood, particularly those relating to work-life balance, economic stability and institutional support for early motherhood.

In short, the study provides relevant information on the global distribution of infertility among women of advanced maternal age and highlights its significant health and social implications, such as population ageing, the growing demand for reproductive treatments and the added pressure on health systems. However, solutions must go beyond the medical sphere and envisage social and structural changes that enable women to exercise their reproductive rights under more favourable conditions.