As long as it remains moderate, regular physical activity has positive effects on many physiological mechanisms, including male and female fertility. Exercising while pregnant is also possible and even recommended, by adapting your practice to pregnancy.

In women

A Boston University study (1) investigated the links between BMI, fertility and physical activity in a cohort of more than 3500 women. The results showed the benefits of moderate physical activity on fertility, regardless of BMI. Thus, compared to women who performed less than an hour of physical activity per week, those who did moderate physical activity for at least 5 hours per week were 18% more likely to get pregnant.

Regular physical activity helps to maintain a healthy weight, and in this way, is beneficial for fertility because being overweight or obesity increases the risks of ovulation disorders. The fatty tissue in fact secretes hormones which, in excess, can disrupt the secretion of gonadotropins (LH and FSH), the main hormones of the ovarian cycle.

In humans

On the male side too, many studies have shown the benefits of physical activity on fertility, and more specifically on sperm concentration.

A 2012 study by the Harvard Public School of Health (2) on 182 men aged 18 to 22 showed significant differences in sperm concentration depending on the level of sedentary lifestyle and physical activity. Men who watched television more than 20 hours per week had 44% lower sperm concentration than men who hardly watched television. Men practicing moderate to intense physical activity for more than 15 hours per week had a sperm concentration 73% higher than men practicing less than 5 hours of sport per week.

An Iranian study (3) attempted to define the intensity of physical activity most beneficial to male fertility by testing a cohort of men aged 25 to 40 years three protocols on treadmills, lasting 24 weeks: moderate intensity training, intense training, high intensity interval training (HIIT). A fourth control group did not engage in any physical activity. The results showed that whatever physical activity improved sperm quality with lower markers of oxidative stress and inflammation. Continuous moderate intensity training (30 min 3 or 4 times per week) was found to be the most beneficial, with sperm volume increased by 8,3%, sperm concentration increased by 21,8%, and more motile spermatozoa with fewer morphological abnormalities.

Previous work from the Harvard Public School of Health (4) presented at the 2013 American Society of Reproductive Medicine Congress highlighted the benefits of outdoor activities and weight lifting on male fertility, with the respective possible mechanism of action the production of vitamin D and the secretion of testosterone.

Exercising during ovulation has no effect on the chances of fertilization if intercourse takes place. Likewise, exercising in early pregnancy does not increase the risk of miscarriage. In more than 70% of cases, the miscarriage is linked to chromosomal abnormalities in the embryo (5).

In women

If moderate physical activity is beneficial to female fertility, practiced intensively, on the other hand, it can have opposite effects.

The results of the Boston study showed that thin or normal-weight women who performed more than 5 hours of sustained physical activity per week were 32% less likely to get pregnant. Other studies, such as the North Trøndelag Health Study (6), had already established a link between intensive or high-level endurance sport (marathon, triathlon, cross-country skiing) and the risk of infertility.

It is recognized in the world of sport, especially endurance and ballet dance, that women practicing intensive or high-level sport often have irregular periods and ovulation disorders. In a situation of intense stress – this is the case when playing high-level sport – the body goes into “survival” mode and ensures its vital functions as a priority. The reproductive function is then secondary and the hypothalamus no longer correctly ensures the secretion of the hormones of the ovarian cycle. Other mechanisms come into play such as a low fat mass which could, like its excess, disrupt hormonal secretions. It is thus proven that a low body weight (BMI less than 18) can reduce the production of GnRH, with consequences of ovulation disorders (7).

Fortunately, the negative effects of heavy training would only be transitory.

In humans

Different studies (8, 9) have pointed out that cycling can alter sperm quality, with decreased sperm concentration and mobility. Various studies (10) have also shown that physical activity practiced intensively could adversely affect the quality of sperm via an increase in body heat, which would alter spermatogenesis. To function properly, the testicles must indeed be at a temperature of 35 ° C (which is why they are not in the abdomen (.

Intensive sport could also affect male libido, suggests a 2017 study (11), and thereby decrease the frequency of sexual intercourse and therefore the chances of conception.

It is quite possible, and even advisable, to continue moderate physical activity during pregnancy if it does not present any complications (twin pregnancy, threat of premature labor, hypertension, IUGR, cervical open bite, placenta previa, disease. cardiovascular, loss of amniotic fluid, rupture of membranes, uncontrolled diabetes 1, severe anemia, history of prematurity).

Numerous studies have demonstrated the beneficial effects of sport in pregnant women in good health, both physically (reduced risks of gestational diabetes, cardiovascular risks, weight gain, natural childbirth favored) and mental (decrease in stress, better self-esteem, decrease in baby blues). If this practice is moderate and supervised by a physician, it does not increase the risk of prematurity, miscarriage, or growth retardation (IUGR) (11).

Physical activity is also part of the hygiene and dietetic rules for the prevention of various pregnancy ailments: constipation, heavy legs, back pain, sleep disorders.

However, you have to choose your activity well and adapt your practice. International recommendations call for 30/40 minutes of moderate-intensity physical activity 3-4 times a week, as well as 30 minutes of muscle building once or twice a week (1).

Which sports to favor?

Walking, exercise bikes, swimming, aqua aerobics and yoga are best used during pregnancy.

Others should be avoided because of the risk of falls, shocks and jolts, in particular: combat sports (boxing, wrestling, etc.), alpine skiing, skating, climbing, horse riding, team sports, altitude sports, scuba diving , exercises lying on the back after the 20th week (due to the risk of compression of the vena cava).

Until when to play sports?

This type of activity can be continued until the end of pregnancy, adjusting the intensity over the weeks.