Laura Kenny: Can elite sport damage women’s fertility?

Laura always wondered if her body was running on empty

Dame Laura, 32, gave her body to cycling for more than a decade. She is Britain’s most successful female athlete.

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

“I took it to the limit – if I wasn’t sick after a race I’d be like, ‘Did I try hard enough?'”

That absolute commitment was rewarded in the velodrome. Two golds at the London 2012 Olympics were followed by two more at Rio 2016.

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

But she miscarried in November 2021 and five months later had an ectopic pregnancy, in which the embryo implants outside of the womb, requiring emergency surgery.

“Everything was a shock – I went from being so in control of my body to being so out of control,” she told Radio 4’s Today programme.

She had never really worried about her own fertility before. Conceiving Albie had been straightforward, and that pregnancy went smoothly. And thankfully, she would successfully give birth to another son, Monty, in July 2023.

But – as Dame Laura began to talk publicly about her baby losses – other athletes told her they had been through the same thing.

It has left a nagging question – could elite sport have a damaging impact on the fertility of female athletes?
“Was my body just running on empty, and then it said, ‘Well, hang on, there’s no way we can do this?'” she says.

Miscarriage is common. The NHS says one-in-eight known pregnancies end before 24 weeks and many occur at a very early stage. Most couples never find out why.

But are athletes at greater risk of any type of fertility problem?

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

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

If they don’t eat enough food to keep up with the calorie burn then issues with menstrual cycles, such as periods stopping for months or even years, are “very common”, Dr O’Donnell says.

Nearly two-thirds of female athletes experience interrupted periods, particularly in endurance sports. There are comparably high rates of periods disappearing in competitors in sports like gymnastics, ballet and figure skating. This compares to only 2-5% of the general population.

Absent periods can be a sign that ovulation (or egg release) isn’t happening.

How does that happen in the body?

“We’re not 100% sure,” says Dr O’Donnell, but the leading idea is that having a baby is so energy-intensive that the brain shuts off reproduction if it thinks there is insufficient spare energy.

It starts in the hypothalamus, a small structure in the centre of the brain that senses the nutritional state of the body.
Sitting just underneath the hypothalamus is the body’s hormone factory – the pituitary gland.

Normally, the gland releases hormones that travel down to the womb and ovaries to control the monthly menstrual cycle and the release of an egg, which makes pregnancy possible.

But if the hypothalamus isn’t happy, this process breaks down and ovulation doesn’t happen.

“If you’re not ovulating you can’t have a baby. You can’t conceive because there’s no egg being released,” says Dr O’Donnell.

The biggest factor in this seems to be the huge number of calories burned while training, which can leave athletes struggling to eat enough food to compensate.

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

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

Fat in the body helps make the sex hormone oestrogen.

“If the sport is affecting body fat content, then quite clearly there’s an effect on oestrogen levels,” she says.

Psychological stress – potentially from the pressures of training and competing – can also disrupt the menstrual cycle.

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

Disruption to periods and egg release is the most clearly recognised impact on a female athlete’s fertility, but this should resolve once they retire from competition, she notes.