Fewer children are being born because conception has become a problem. Here's what the latest research, especially on men's health, has revealed

As Le Monde notes, evidence of increasing infertility is becoming more convincing: according to international estimates, based on regional studies conducted from 1990 to 2021, one in six people worldwide (about 17.5% of the population) has at least once in their life faced the inability to conceive a child within a year of regular unprotected sexual activity without contraception.

This figure remains consistently high in both high-income countries (17.8%) and low-income countries (16.5%).

The state of men's health is particularly alarming: studies show that the average sperm concentration in male semen worldwide fell from 101 to 49 million per milliliter between 1973 and 2018. Thus, the global average was on the verge of the 40-50 million per milliliter threshold, below which the probability of conception begins to rapidly decrease.

Against this backdrop, the demand for assisted reproductive technologies (ART) is constantly growing. In France, the proportion of children born with medical intervention has been increasing linearly for forty years and now accounts for almost 4% of the total, which is equivalent to one child in every school class. In Denmark, this figure is even higher, reaching 10%.

Social factor

However, many demographers urge not to overstate the automatic impact of biology on statistics. They insist that the main drivers of declining birth rates remain social factors: lack of stable employment, housing problems, and difficulties in combining a career with family life.

Age is a key factor in this debate. Infertility often results from the decision to postpone childbirth until a later date. While at 25 years old the probability of conception in one cycle is 25%, at 35 it drops to 12%, and at 40, to 6%.

Ecology

Nevertheless, researchers from the University of Copenhagen argue that socio-economic models do not account for the "price of industrialization" — environmental pollution.

Researcher Niels Skakkebæk was one of the first, back in the 1990s, to describe the global decline in sperm count and to identify a link between male infertility and testicular cancer, the incidence of which is rising among young men.

To date, the hypothesis of the ecological origin of these pathologies is a priority. This refers, in particular, to the exposure to pesticides and endocrine disruptors.

Danish researchers have developed a new indicator — "total rate of pregnancies without medical assistance". It covers all natural conceptions, including both live births and abortions, but excludes those births that were made possible only through reproductive technologies.

The analysis showed that the natural ability of the population to reproduce began to decline much earlier and more rapidly than it became noticeable according to official birth statistics. This is explained by the fact that the development of medical assistance and artificial insemination long "masked" the real deterioration of the population's biological potential.

Lifestyle

Besides ecology, lifestyle also has a significant impact, especially in the six months prior to the start of pregnancy. Smoking, alcohol, and poor nutrition negatively affect germ cells, all stages of conception, and the subsequent development of the future child—both at the embryonic and fetal stages.

In particular, a recent study by scientists from the Institute of Molecular and Cellular Pharmacology (Sophia Antipolis technology park) showed that the consumption of ultra-processed foods and an excessive number of calories are directly linked to a decrease in testosterone levels and the number of motile sperm.

Scientists call for the immediate implementation of national strategies to combat infertility, based on the cooperation of medical professionals and demographers. The main goal is to provide people with truthful information about the risks associated with age and the environment, without putting pressure on those who consciously choose a child-free life.

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