Japanese ultrarunner Tomomi Bitoh is a doer.
When she made the choice to freeze her eggs so she could become pregnant once she’s ready, she did it without thinking twice. In November 2023, a month before her 33rd birthday, she headed straight to a Tokyo clinic from the airport after completing a 170-kilometer high-altitude trail running race in the Himalayas.
“I didn’t ask anyone for their opinion. I didn’t even tell my parents. I’ve always known what I wanted for myself,” Bitoh, now 34, said. “I want to have a baby one day. Just not now.”
As one might imagine, ultrarunning, which is anything longer than a standard 42.195-km marathon, isn’t exactly a fertility-friendly sport. Athletes push their bodies to extremes, running for hours and hours at a time, often on little food and water and without a break.
Bitoh has run some of the most brutal races in the world — in the mountains, deserts, jungles, icy terrains and other not-so-pleasant places. She started out 2025 by successfully completing seven marathons on seven continents in seven days as part of the World Marathon Challenge. She is a self-proclaimed running addict.
“Running consumes my life. I feel antsy when I’m not running,” Bitoh said earlier this month on the day she was flying out to Australia to take part in a 520-km, 10-day multistage race.
Bitoh, who went from a nursery school teacher to a personal trainer to a professional runner, ran her first full marathon when she was 27. Since 2022, she has been employed by a company that allows her to train full time.
She has a list of endurance adventures she hopes to check off in the next two years, which is why she chose to delay motherhood. It was also an abnormal pap smear, a screening that can detect early signs of cervical cancer, that got her to act quickly to freeze her eggs.
“It turned out to be a false alarm, but it scared me a little. It got me thinking about the medical what-ifs,” said Bitoh.
“I don’t have a partner now, but that’s not going to stop me from becoming a mother. If everything goes according to plan, I’ll win the 40th edition of the ultramarathon in the Sahara Desert in 2026 and give birth in 2027. Then, I’ll make my competitive comeback. I believe in manifestation.”
Social egg freezing, also known as elective egg freezing, is a process in which a woman's eggs are collected, frozen, and stored for potential future use. This is done for nonmedical reasons, such as pursuing career or educational aspirations, or waiting to find the right partner.
The best time to freeze your eggs is before the age of 36, according to the Japan Society for Reproductive Medicine. Generally, egg freezing at an earlier age ensures better quality eggs and lessens the risk of complications later during pregnancy attempts.
Although there's technically no cutoff age for egg freezing, Grace Sugiyama Clinic Shibuya, the private fertility clinic that Bitoh used, discourages egg freezing for those over the age of 39. The average age of patients undergoing the freezing procedure there is 35.
While pointing out that egg freezing is not a 100% guarantee of a successful pregnancy down the line, Yuka Okada, head of the clinic, said 15 frozen eggs by the age of 33 could lead to a 90% chance of having one live birth.
“Some reports say the odds of success are low, but the reality is that egg freezing, if done at the right time, is a safer bet than starting fertility treatments in your 40s,” Okada said.
More women in Japan are expressing interest or following through with freezing their eggs in recent years, but only a few athletes in Japan — including Bitoh, ice dancer Misato Komatsubara and snowboarder Tomoka Takeuchi — have spoken publicly about their personal experiences.
Bitoh shared each phase of her egg-freezing journey in a YouTube video, giving viewers a unique and personal look at what to expect from the process. In the video, she shows herself injecting her stomach with hormones before the egg retrieval procedure and reports post-procedure that 13 mature eggs were retrieved.
“I think 13 is a lot, and I got super lucky,” Bitoh said in the interview. “Even then, there’s no guarantee of a baby. I understand that this path isn’t for everyone, but I have a job with a high risk of injury, so it made sense to me. I didn’t want to have any regrets later.”
Bitoh has spent around ¥450,000 on one cycle of egg freezing, and she is paying ¥4,000 a month as a storage fee. She will eventually get all of her money back as her company offers egg-freezing benefits.
Tokyo partially covers egg-freezing costs for women age 18 to 39. Yamanashi and Osaka prefectures and the city of Kashiwa in Chiba Prefecture also use public funds for such purposes.
In the U.S., some women’s sports teams now even pay for egg freezing and in vitro fertilization. Elite athletes, including tennis stars Sloane Stephens and Maria Sharapova, are making egg freezing less taboo by talking about it as a viable option for those who want to preserve their fertility and delay childbirth.
Bitoh says Japan is not quite there yet. She can see how navigating egg freezing can be particularly tricky for athletes who belong to a team or work with big name sponsors as they would need to take time off from their sport to schedule each cycle. The process took Bitoh about two weeks, during which intense physical activity was prohibited.
“One of the biggest concerns for athletes considering egg freezing is when to do it. I create my own race schedule, so I was able to block off an entire month in my calendar and make those frequent medical visits. Most athletes won’t be able to do that. For women in sports, there are many added layers of complexity,” Bitoh said.
Okada applauded Bitoh’s decision to talk about freezing her eggs and educate other hopeful mothers about their reproductive choices.
“For many athletes, the age of peak performance overlaps with their age of peak fertility. Egg freezing is an option for those who wish to have children later in life as pregnancy rates decrease in the late 30s, even with assisted reproductive technology,” the doctor said.
“It’s good that athletes are speaking openly about this topic because they are spreading awareness about egg freezing. Whether you’re an athlete or a nonathlete, egg freezing is a personal decision that depends on various factors. It’s important to understand your body and how to care for it when you’re young, and an OB-GYN checkup is a good place to start.”
Bitoh says freezing her eggs has given her peace of mind — knowing that she doesn’t have to rush into decisions about starting a family — and that’s all she ever wanted. She doesn’t even know if she’ll end up using her frozen eggs.
“Who knows what the future holds. I may find love and get pregnant naturally, and not need the frozen eggs. But if I need them, my future self will be grateful I did this.”
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