Can elite sport damage women’s fertility?

Olympic gold medalist Dame Laura Kenny is Britain’s most successful athlete. She has two young sons, but she also had a miscarriage and an ectopic pregnancy, and always wondered whether the physical toll of elite sport had compromised her fertility. The BBC News Health team investigated the matter.

Ms Laura, 32, has given her body to cycling for more than a decade.

“In every training session I went there to give 100%, and in every race I went there to give 100%.

“I’ve reached my limit. If I wasn’t sick after the race, I’d say, ‘Did I try hard enough?’

This absolute commitment was rewarded on the race track. Two golds at the London 2012 Olympics, followed by two more golds at Rio 2016.

She married fellow cycling phenom Jason Kenny later that year and the couple welcomed their first child, Albie, in 2017. She then claimed another gold and silver medal at the Tokyo Olympics (held in 2021).

But she had a miscarriage in November 2021, and five months later she had an ectopic pregnancy, where the fetus implants outside the uterus, requiring emergency surgery.

She told Radio 4’s Today programme: “It was all a shock, I went from being in control of my body to being out of control.”

Ms. Laura had never been worried about her fertility before. Getting pregnant with Albie was simple and went smoothly.

But since she first spoke publicly about losing her child, other athletes have told her they went through the same thing.

It left a nagging question: Could elite sport have a detrimental effect on the fertility of female athletes?

“My body was running on empty, and then it said, ‘Okay, wait, there’s no way we can do this?'” she says.

Miscarriage is common. About one in four pregnancies ends before week 24, many of which occur very early. Most couples never know why.

But are athletes more at risk of developing any type of fertility problems?

Dr Emma O’Donnell, an exercise physiologist at Loughborough University, says the lifestyle of a professional athlete places unique stress on the human body.

Elite training burns an enormous number of calories, and as a result, athletes’ bodies are often lean and muscular, with very little body fat.

If they don’t eat enough to keep up with their calorie burning, menstrual problems, such as menstrual cycles stopping for months or even years, are “very common,” says Dr. O’Donnell.

Nearly two-thirds of female athletes experience intermittent periods, especially in endurance sports. There are relatively high rates of amenorrhea among female competitors in sports such as gymnastics, ballet and figure skating. This compares to only 2-5% of the general population.

Absent menstruation can be a sign that ovulation (or egg release) has not occurred.

“We’re not 100 percent sure,” says Dr. O’Donnell, but the key idea is that having a baby takes so much energy that the brain shuts down the reproductive process if it thinks there’s not enough spare energy.

It begins in the hypothalamus, a small structure in the center of the brain that senses the nutritional status of the body.

Directly below the hypothalamus is the body’s hormone factory – the pituitary gland.

Normally, the gland secretes hormones that travel to the uterus and ovaries to control the menstrual cycle and release of the egg, making pregnancy possible.

But if the hypothalamus is not happy, this process is disrupted and ovulation does not occur.

“If you don’t ovulate, you can’t have a baby. You can’t get pregnant because no egg is released,” says Dr. O’Donnell.

The biggest factor appears to be the sheer number of calories burned during training, which can leave athletes struggling to eat enough to compensate.

This phenomenon is known as relative energy deficiency in sport (RED-S), and was first recognized by the International Olympic Committee In 2014.

But there are also likely to be other factors at play, says Professor Geeta Nargund, a consultant at St George’s Hospital and medical director of Create Fertility.

Body fat helps produce the sex hormone estrogen.

“If exercise affects body fat content, it’s pretty clear that there’s an effect on estrogen levels,” she says.

Psychological stress – which may be caused by the pressures of training and competition – can disrupt the menstrual cycle.

“We see this in women who have high levels of anxiety,” Dr. O’Donnell said.

She points out that interruption of menstruation and egg release is the most obvious impact on female athletes’ fertility, but this must be resolved once they retire from competition.

For those who succeed in conceiving, things can still go wrong. After the egg is fertilized, it must implant in the lining of the uterus. However, in an ectopic pregnancy, the egg implants elsewhere, usually in the fallopian tube that connects the ovaries to the uterus.

About 11,000 pregnancies a year in the UK are ectopic. It’s not entirely clear why they occur, although inflammation and scar tissue in the fallopian tube can increase the risk.

“But in this case, I don’t see a direct link between exercise and an increase in ectopic pregnancies,” said Professor Nargund, who has treated athletes struggling with their fertility.

However, she said there is a possible link between too much intense exercise in the first trimester of pregnancy and miscarriage, although more research is needed to confirm this.

She pointed out A large Danish study Which followed more than 90,000 women and suggested that the more intense exercise women did, the greater the risk. This was especially true for weightlifting and high-impact exercises.

“If you end up in Laura Kenny’s zone where you’re an elite athlete, you’re at the top of that,” Professor Nargund said.

But she explained that the results should be taken “with caution” because the way the study was designed meant there could be other explanations that were not taken into account.

Meanwhile, a very small study of 34 Norwegian athletes They found no increased risk of fertility problems, including miscarriage.

“We need to do more research when it comes to sport, exercise, hormone balance and reproduction,” says Professor Nargund.

Lauren Nicholls played netball at elite level for 10 years and then had two children, before becoming coach of Premier League champions Loughborough Lightning. She says the conversations current female players have about fertility are different from those she has with her teammates.

“I know a few female players who are a little older who froze their eggs and made those decisions for their families later on,” she says. “Because they’re worried about their careers.”

Juggling being an elite athlete and raising a family has always been a difficult challenge. For women, their peak fertility years overlap with the time they reach their physical peak.

Male athletes as well Not immune to fertility issues. Burning more energy than you have may affect testosterone levels, cause sperm abnormalities and even erectile dysfunction.

But for Dr Emma Bullen, an exercise researcher at Loughborough University, the lack of definitive answers about the impact of elite sport is a symbol of how little research has been done on female athletes, from fertility to injury risk.

She said the research is “trying to catch up” with the amount of interest in male sports.

“We are seeing the repercussions of this as women’s sports become more professional and the number of female athletes is greater than ever before,” adds Dr. Bolin.

In general, Professor Nargund says female athletes are more likely to face fertility challenges than other women.

“There seems to be a fertility problem due to [elite sport’s] “Potential impact on ovulation, including potentially increased risk of miscarriage,” she says.

But the final answer to how much exercise is excessive at the elite level is not clear. That’s enough for Lady Laura for now.

“I feel like the conversation itself is really important because I want people to start talking,” Laura says. “Honestly, I would have loved it to have been more open.”

However, the relationship between exercise and fertility affects all of us, even if we are far from Olympic glory.

Most men and women benefit from exercising and losing excess weight before trying to conceive, as this is known to enhance fertility.

Regular physical activity reduces stress, improves sleep and makes menstrual cycles more regular in those with hormonal polycystic ovary syndrome (PCOS).

But amateur athletes who train intensely can end up running on empty and see their periods stop, or become irregular.

“It’s not to the same degree, but it’s there,” Dr. O’Donnell says.

She adds that ensuring there is a balance between energy intake and energy production is “really important for ovulatory cycles” and key to maintaining reproductive function.

“[Amateur athletes] “They don’t really realize how many calories they really need to meet their energy demand.”