In 1672 the eminent Dutch physician Regnier de Graaf published one of the defining works in the history of biology, unravelling many of the mysteries of the human reproductive system at a time when microscopic techniques were still in their infancy.
But alongside De Graaf’s many detailed sketches explaining how the ovum passes from the ovaries to the uterus, is a striking if rather morbid note - “As a foetus grows, it prepares death for its mother.”
De Graaf’s comments should perhaps be added in the context of their time. In the 1600s, it’s estimated that 1000-1500 women did not survive childbirth for every 100,000 live births. But his words also reflect a perception which was still very much in vogue 300 years later – namely, that the process of pregnancy was in some ways the beginning of the end for a woman’s youth and, in the eyes of 20th century coaches, her ability to perform at the highest level as an athlete.
A quick scroll through the annals of sporting fame reveals plenty of anecdotal counter-evidence. At the 1948 London Olympics, mum of two Fanny Blankers-Koen became the toast of the city after surging to victory in the Games’ blue ribbon events - the 100m and 200m. On the tennis court, Australia’s Evonne Goolagong largely dominated Wimbledon 1980 three years after having her first child.
Yet it’s only been over the past two decades that the notion has begun to be seriously challenged. Liz McColgan’s 1991 World Championship victory in the 10,000m as a new mum was greeted with a mixture of astonishment and disbelief. Having a child while harbouring ambitions of sporting glory was even considered unprofessional in many circles.
It wasn’t until Paula Radcliffe’s sustained success in high-profile marathons after the birth of her first child in 2007, that the intriguing idea of pregnancy actually providing a boost to women’s abilities in endurance competition, first began to take hold.
It’s a captivating suggestion, largely because it challenges some of the most fundamental assumptions surrounding women’s bodies and their hormonal cycles. Michelle Mottola, an exercise physiologist at the University of Western Ontario, believes there is evidence to suggest it may be more than just myth.
“With all the physiological changes that occur during pregnancy, it’s not like you can turn the valve off and switch back to normal once the baby’s born,” she says. “The postpartum period can potentially last up to a year afterwards. And of course everything depends on the woman, the birth, and her training regimen. But scientific evidence suggests that, in some ways, she may find performance a bit easier during this period because of the changes to her heart and her lungs.”
One particular change which could prove hugely beneficial to endurance athletes is the expansion of the ribcage during pregnancy, assisting breathing. But the alterations which may have the most impact on athletic ability are those to the cardiovascular system. During pregnancy, a woman’s heart is essentially remodelled. While the thickness of the heart walls remains the same, the chamber capacity increases, enabling it to hold a much larger volume of blood. This increases the efficiency with which oxygen is supplied to the muscles, the same mechanism induced by blood doping. With blood being pumped at a far greater rate around the body, in theory, the heart should be able to function more effectively during physical activity, until the system reverts back to its original state.
However, in the short term, the practicality is rather different to the pure physiology as Jo Pavey can testify. In August Pavey won European 10,000m gold for the first time at the age of 40, after the birth of her second child in September 2013. She faced a constant battle against the clock, returning to full training just a few months before the British trials.
“Of course my priority is totally being a mum but it’s a strange situation as pregnancy creates the need to come back from such a low level of fitness and you wonder how much that outweighs any benefits,” she says.
“As an elite athlete you go from running 100 miles a week and doing sessions down the track till you lie on the floor to doing 35-40 minutes of jogging a day for nine months. So it’s a long road back. Earlier this year I was down the track doing times which are so ridiculously horrendous. For 800m repetitions, I’d be doing each one at least 20 seconds slower than I should, which is a massive amount of time for a race which lasts 2 minutes. Even if you were injured you’d never get that unfit.”
In reality, trying to attempt to return to racing soon after childbirth can also put an athlete at risk of illness and injury, something Pavey knows only too well. Recovering from C-section surgery and dealing with sleepless nights leaves the body in a weakened state, and after the birth of her first child in 2009 she sustained a stress fracture in her foot.
“There’s always that risk that the body has gone through so much change and it’s all a bit too sudden,” she says. “My left foot lengthened during the pregnancy due to the ligaments going softer and that changed the mechanics of the foot. I still have to wear a bigger shoe on it now.”
But barring complications, Mottola believes that some women may experience benefits emanating from the physiological remnants of their pregnant state after about a year, depending on how well they have been able to recover. It may be no accident that Pavey won her first European gold around 11 months after giving birth.
“It does depend on many different factors – how much weight she gained during pregnancy; whether she is still breastfeeding,” she says. “Obviously excessive weight gain would make things far harder.”
However while the purely physiological changes induced by pregnancy may last only through the postpartum period, could the hormonal changes remain in the body for far longer, allowing athletes to reap the benefit in the long term?
Higher levels of oestrogen are released during pregnancy, a hormone which can increase water retention and minimise fatigue during racing by stimulating the release of serotonin. How long these levels of oestrogen remain present remains currently unknown, as examining this scientifically presents a considerable challenge.
“It would be very difficult to design a controlled study in that regard, purely because there are so many potentially confounding factors – how the pregnancy went, how the birth went, was a C-section required,” Mottola says. “It is possible that pain threshold could improve but that’s hard to monitor as many women have medicated deliveries.”
As a result most of the evidence remains anecdotal, but there are intriguing hints. For Pavey, changes in her hormonal profile since birth have proved a boon.
“I’ve always had problems with my blood sugar going really, really high when I race which makes me feel ill but that seems to have settled down since I’ve had children,” Pavey says. “And my menstrual cycle is also not as disruptive to my running as it used to be. It’s no longer encroaching on the whole month and that’s definitely helped especially this season. Your body definitely seems to calm down once you’ve reproduced.”
However potential benefits which endurance runners may enjoy are not likely to be so useful for those involved in more explosive disciplines. Sprinter and three-time Olympic silver medallist Merlene Ottey once commented that her ability to continue racing internationally until the age of 52 was because she’d never married or had children. According to Mottola this is simply down to the very nature of pregnancy.
“Pregnancy’s more of an endurance physical conditioning change than, say, an anaerobic or short-distance change,” she says. “It’s a long-term commitment of the body over 40 weeks for a variety of different adaptations. So it does make sense that long distance runners may see better performances after having children than those who compete over shorter distances.”
