20-04-2025
The most impressive finisher from Saturday's Boston 5K? Reilly Kiernan broke 20 minutes — while eight months pregnant.
Kiernan, a Jamaica Plain resident who runs for the Tracksmith Boston Hares racing team, isn't quite your average 5K fun-run competitor. She was an All-Ivy League runner at Princeton and continued running competitively after college, qualifying for the US Olympic Marathon Trials in 2020.
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Kiernan was twice among the 50 fastest female finishers at the Boston Marathon, running 2:46:36 in 2021 and 2:49:33 in 2024, the latter coming just a year after she had her first child.
'This is my second pregnancy, and I was able to run healthily up to 24 hours out from giving birth to my son, and I did run a couple of races in that first pregnancy,' Kiernan explained. 'Just for fun, not all-out efforts, but just to still be part of the community and vibes and race day and mix it up a little bit. Having had that positive experience the last time, I thought I would try it again this time.
'The marathon weekend is such a fun running weekend in Boston, I've run the marathon [multiple times], I ran last year. I thought it would be fun to still be part of the fanfare and good vibes of marathon weekend but in a shorter, more-appopriate-to-being-eight-months-pregnant kind of way.'
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Reilly Kiernan was 35 weeks pregnant when she finished sixth in her age group in the Boston 5K.
Courtesy of Reilly Kiernan
Thanks to the pregnancy deferral program, Kiernan was able to defer her Boston Marathon entry to 2026, where she hopes to back running the full distance from Hopkinton to Back Bay.
Kiernan raced the BAA 5K in 2022, coming second in her age group in 16:40. Saturday's effort — still quick for many — was a little less serious and a little more fun, considering her due date for her second child (a girl this time) is May 25, putting her just five weeks out when she toed the line Saturday.
'It definitely feels different, definitely no pressure, just doing it for fun and making sure I keep the effort under control,' she said. 'But I think the fun thing about the 5K is that it is that kind of kickoff to marathon weekend. Being in the crowd with people from all different countries, people who are using it as a tune-up for the race on Monday, or people who are just using it in the same way that I did, to be part of the celebration of the weekend, you can't help but get some of the positive energy and momentum of that.'
Amin Touri can be reached at
