We talk about infertility when no pregnancy is declared after 1 or 2 years of regular and unprotected intercourse. It is important to distinguish infertility from sterility, where sterility refers to the irreversible inability of the couple to naturally conceive and give birth to a healthy child. In contrast, most types of infertility can be treated with medical procedures or laboratory techniques.

In the absence of any abnormalities, a fertile and healthy couple has no more than a 1 in 4 chance per cycle of having a pregnancy. Natural reproduction assumes that the different genitals in women (ovaries, tubes, uterus) and in men (testis, excretory ducts) are in good coordination and that sexual intercourse takes place at the right time vis-à-vis ovulation.

The causes of infertility are multiple and affect both men and women with the same frequency. Infertility in couples can have multiple roots. In women, for example, one of the most common causes is a decrease in ovarian reserve (from the age of 35), an ovulation disorder or the presence of a disease such as endometriosis.

Impact of weight on fertility

For men: Numerous studies published over the past two decades have observed altered sperm parameters associated with body mass index (BMI). These publications suggest that a high BMI in obesity, or even overweight, involves a decrease in sperm concentration, a decrease in the number of motile sperm, an increased risk of developing oligozoospermia (abnormally low amount of sperm) or azoospermia (complete absence of sperm), or an increase in the presence of atypical forms of sperm. These studies also seem to suggest a link between obesity or overweight and the quality of sperm in a sample (DNA fragmentation).

For women: most epidemiological studies carried out to date indeed show a link between a woman’s weight at conception and the chances of pregnancy. The body mass index BMI is a major factor in the risk of infertility due to anovulation (absence of ovulation). The higher a BMI in women, the more this risk is multiplied. Therefore, there is an increased probability of taking more than a year to conceive a child in the case of obesity or overweight in women.

To that end, weight represents a major factor in the risk of infertility, both in men by alteration of spermatic parameters, and in women by anovulation.

Infectious causes

Certain infectious pathologies, especially sexually transmitted infections, represent a major cause in the deterioration of fertility in couples. One of the most common infections in women is pelvic inflammatory disease. Urogenital and inflammatory infections or infections of the genitourinary tract are also an important factor in infertility in men.


Numerous studies also suggest that chronic alcohol intoxication is one of the causes in the alteration of spermatic parameters in men, involving a decrease in sperm volume, sperm concentration as well as sperm mobility and, would also affect sperm morphology.

Environmental factors :

Often overlooked, many environmental factors have been associated with impaired fertility and cited in a number of scientific publications, for example:

    • Tobacco: suspected of reducing sperm concentration in men
    • Air pollution resulting in particular from road traffic
    • Metals: Several cases have shown that male exposure affects sperm parameters.
    • Pesticides
    • Ionizing radiation
    • Electromagnetic fields