"Since I was a child, there were always three things I wanted: To be an Olympic gold medallist, a wife and a mom," said the 33-year-old world silver medallist.
"Right now I am two for three and I'm feeling the urge to be someone's mom.
"So this is it for me."
In doing so, she hopes to end her career on an ambitious note before returning home to Illinois with plans to open a health food restaurant.
"I want to run a personal best - it's 12.37 now - and win the Diamond League final," said the two-time Olympic medallist.
That's a tall order in an event where U.S. compatriots dominate and the world record is 12.20 seconds, set by American Keni Harrison in 2016.
But overcoming obstacles has always been a Harper Nelson trademark.
"People don't understand. I had surgery in February 2008, still made the (Olympic) team and won," said the Bob Kersee-trained athlete.
A big underdog in that race, having been hurdling professionally for only a year, she surged to gold when favoured team mate Lolo Jones heartbreakingly clipped the ninth hurdle and broke stride.
Four years later Harper Nelson was in another dramatic final, losing the 2012 Olympic gold to Australia's Sally Pearson by 0.02 of a second.
Both medals are often on display when the American speaks to groups.
"The (2008) ribbon is kinda getting torn up, but it shows all that I have been through," she said.
Along with the 2008 surgery, she also suffered injuries in 2010 and 2016 and served a three-month doping ban in 2016-17 for inadvertent use of a medication containing a banned diuretic prescribed for her high blood pressure.
But she bounced back even after not making the U.S. Olympic team in 2016.
"I've always felt like I had a challenge," Harper Nelson said. "And I want the world to remember me as a fighter and a clutch performer."
Last year's world championship silver medal was especially pleasing.
"It was another defining moment for me," said Harper Nelson. "It showed me I didn't have to fight to prove I am one of the best.
"And through it all I kept my love for the sport."
(Reporting by Gene Cherry in Raleigh, North Carolina, editing by Pritha Sarkar)
