But even with these anecdotes, exactly how to safely and most effectively pair athletics and motherhood is still a bit of a scientific gray area. Stacy Sims, an exercise physiologist, sports nutritionist, and senior research fellow at the University of Waikato, in New Zealand, studies sex differences among athletes. She told me that only in the past five to seven years have scientists begun to seriously approach physiological questions related to the female athlete and pregnancy, reproductive systems, hormones, and the menstrual cycle. The enactment of the WNBA’s maternity policy could do more than help support moms in the league, Sims said. It could also help researchers like herself have more incentive, and more cases, to study the physiology of pregnant and postpartum athletes. “The WNBA saying, ‘Hey, we’re putting this in’? I’m like, ‘It’s about effing time,’” Sims said. Now that the sports culture is changing to be more accepting of pregnant athletes, she said, the research that needs to be done “comes down to the health and safety of the athletes.”
According to Sims, some physiological effects of being pregnant could actually have a positive effect on athletic performance, such as increased blood volume, higher pain tolerance, and a better ability to access the parasympathetic nervous system (managing stress better). The new policy could also help reduce the risk of injuries that women who give birth are more likely to face, especially mothers in the postpartum period, when women’s bodies tend to need more rest and recovery. “This maternity leave is really going to help female athletes to have that ability to relax and not worry about losing [pay] and not have the pressure to perform [too soon],” Sims said. But there are still many unknowns that she hopes to dive into. “The research is still very archaic.”
Georgie Bruinvels, a research scientist who co-created FitrWoman, an app that tracks menstrual cycles and physical activity, agreed, telling me that pregnancy isn’t the only unknown. The discussion of female athletes and how they’re affected by everything from puberty to menopause has historically been avoided in research in the medical and sports-science worlds. This is due, at least in part, to the constant fluctuation of women’s hormones throughout the menstrual cycle, which makes them “more complex” to perform research on, she said. Not long ago, for instance, women and girl athletes were often told it was normal to lose their periods while training hard, something now known as a sign of a probable nutrient deficiency.
That’s why Bruinvels, an elite runner herself, has started studying the effect of the menstrual cycle on female athletes; her research reportedly gave the U.S. Women’s National Soccer team an edge in their 2019 World Cup championship run. Just tracking this kind of information, Bruinvels said, can “empower women with the understanding of how to use it to their advantage.”