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How does sport affect fertility? Does BMI matter? We answer your questions
At Vida Fertility, each case is different, unique, and every story matters.
Many people who come to our clinics in Madrid and Alicante ask a recurring question:
“Can my lifestyle, the way I train or my weight be affecting my fertility?”
The answer is yes — sport has a direct impact on fertility, both positive and negative. The key lies in balance.
In this article, we speak with Dr Marta Zermiani, fertility specialist at Vida Fertility, about how physical activity affects reproductive health, which types of exercise are beneficial when trying to conceive, and which situations require adjusting or even stopping training.
What is the relationship between sport and fertility?
Exercising regularly improves cardiovascular health, regulates blood sugar, reduces stress… and can also boost reproductive function. However, excessive training, inappropriate exercise types or an unbalanced BMI may have negative consequences.
How does sport affect the reproductive system?
Moderate exercise helps improve physical endurance, maintain a healthy weight, strengthen bones and lower the risk of cardiovascular disease.
Sport and female fertility
Many women of reproductive age include physical activity in their daily routine — and in most cases, it’s highly beneficial:
- It supports regular ovulation when done in moderation
- It helps lower cortisol and anxiety levels, which impact the menstrual cycle and embryo quality
However, excessive or poorly managed activity can negatively affect the menstrual cycle. This can lead to:
- Hormonal imbalances resulting in luteal phase deficiency
- Amenorrhoea, or the complete absence of menstruation, which may lead to female infertility
- Poor implantation outcomes if high-impact exercise is done just before an embryo transfer
Sport and male fertility
Physical activity practised in a moderate and balanced way can be a powerful ally for male fertility.
In overweight or obese men, regular exercise helps improve semen quality by enhancing sperm production, reducing systemic inflammation, and balancing hormone levels, including testosterone.
On the other hand, excessive sport (e.g. bodybuilding, high-intensity training) may have the opposite effect.
Anabolic steroids, extreme calorie restriction or overtraining can suppress natural testosterone production and significantly reduce sperm quality, leading to oligozoospermia or even temporary azoospermia (absence of sperm in the ejaculate).
Does exercise increase fertility?
As long as it’s practised in moderation and tailored to the individual, physical activity can have a very positive effect on fertility.
Regular exercise not only improves physical health but also promotes mental and emotional balance, which is crucial when trying to conceive.
In women, it helps regulate ovulatory cycles and improves ovarian response in fertility treatments.
In men, it can enhance sperm quality, particularly in overweight individuals.
Exercise also supports healthy body weight, insulin regulation, stress reduction and pelvic circulation — all of which create a more favourable environment for conception.
However, as our specialists at Vida Fertility point out, excessive or extreme exercise can have the opposite effect, disrupting hormonal balance and reproductive function.
According to Dr Marta Zermiani:
“The key is to find balance, and if you’re undergoing fertility treatment, always follow your doctor’s advice for each phase of the process.”
BMI, exercise and fertility: what we observe in clinic
Dr Marta Zermiani, gynaecologist and fertility specialist at Vida Fertility, has observed a clear correlation between body mass index (BMI) and reproductive outcomes.
“Women with a very low BMI —especially elite athletes or those engaged in extreme training such as crossfit, triathlon or long-distance running— often have irregular cycles or amenorrhoea.
Conversely, overweight women who begin a structured physical activity programme see improvements in ovulation within just three months.”
In men, moderate activity improves sperm quality.
However, among those who train with heavy loads or use unregulated supplements, there is a marked decrease in free testosterone and oligozoospermia.
What are the best exercises to help you get pregnant?
The key is to maintain moderate, consistent and personalised physical activity.
At Vida Fertility, we recommend:
FAQs about sport and Fertility
During IVF or artificial insemination treatment, it is essential to adapt your exercise routine.
“There are sensitive phases of the cycle when the body needs to slow down. Just ovarian puncture or right before embryo transfer, we recommend complete rest or low-impact activities. The uterus must be calm and well-perfused,” explains Dr Marta Zermiani.
At Vida Fertility, we advise adjusting, reducing, or increasing physical activity depending on each patient and the stage of the fertility process:
- ✔ During stimulation: gentle walks, light yoga
- ✘ After egg retrieval: relative rest for 48 hours, no abdominal exercises
- ✘ Before transfer: avoid running or jumping
- ✔ During the Beta wait: low-impact, gentle activity only
When can sport negatively affect fertility?
There are certain clinical indicators that suggest sport may be negatively influencing fertility:
- Absence of menstruation in athletes with a low BMI (<19)
- Hidden eating disorders linked to overtraining
- Hormonal disruptions in women undergoing intense strength training
- Abnormal semen analyses in men who use anabolic steroids
- Failed implantation in patients engaging in intense training after embryo transfer
In such cases, our medical recommendation is always to prioritise hormonal and reproductive health over short-term physical performance.
If you’ve been trying to conceive for six months to a year without success, there may be an underlying fertility issue.
Vida Fertility is made up of some of the best fertility specialists in Spain. Get in touch — we’re here to help.
Having an active lifestyle is a good thing.
But when trying for a baby, it’s important to adapt your physical activity with the right medical guidance.
Wondering whether your current fitness routine might affect your fertility?
Book an appointment with Dr Marta Zermiani at Vida Fertility and receive a personalised plan combining reproductive health with physical and mental wellbeing.
FAQs on sport and fertility
Do I need to stop exercising to get pregnant?
Dr Marta Zermiani answers:
No, except in extreme cases. At Vida Fertility, we don’t demonise exercise. On the contrary — we prescribe it as a tool to increase your chances of success during fertility treatment.
Our experience shows that:
- 30 minutes of moderate activity a day improves hormonal balance
- Exercise reduces systemic inflammation, which is key in cases of endometriosis
- Gentle physical activity helps oxygenate the uterus and prepare for embryo implantation
What are Kegel exercises??
Dr Marta Zermiani answers:
Kegel exercises involve voluntarily contracting and relaxing the pelvic floor muscles. Their aim is to strengthen the muscles that support the pelvic organs — including the bladder, uterus, small intestine, and rectum.
The main benefits include:
- Preventing or improving urinary incontinence, especially stress incontinence
- Better control of bowel function
- Enhanced sexual health
They may also help prevent pelvic organ prolapse, such as descent of the bladder, uterus, or rectum.
A major advantage is that Kegels can be done anytime, anywhere — while eating, driving, sitting at your desk, or resting.
Does exercise improve fertility?
Dr Marta Zermiani answers:
Yes and no — let me explain.
Regular exercise brings many health benefits: improved blood circulation, better cardiovascular function, lower cholesterol, increased stamina, and stronger bones and muscles.
It also helps control body weight, stabilise blood sugar levels, reduce stress, and improve both sleep and emotional wellbeing.
All of these contribute to better overall health and personal wellbeing, which can indirectly support fertility.
However, this does not mean that someone who exercises regularly is automatically more fertile.
The most decisive factors for fertility are age and the health of the reproductive system.
