Six-time Olympic gold medallist Allyson Felix says female athletes will "no longer be financially penalised for having a child" after Nike changed its contracts for pregnant athletes.
In a letter shared by Felix on social media, Nike says it will "not apply any performance-related reduction" for 18 months if an athlete becomes pregnant.
Felix's daughter Camryn was born prematurely in November.
In May, she said Nike wanted to pay her 70 per cent less after she became a mother.
Writing in the New York Times at the time, Felix, 33, said: "I asked Nike to contractually guarantee that I wouldn't be punished if I didn't perform at my best in the months surrounding childbirth.
"I wanted to set a new standard. If I, one of Nike's most widely marketed athletes, couldn't secure these protections, who could? Nike declined."
Felix returned to racing for the first time in 13 months in July at the US National Championships. After the meet, she decided to not renew her Nike contact and joined women's athletic wear company Athleta.
On social media on Friday, Felix posted a picture of the letter from Nike executive vice president of global sports marketing John Slusher. She wrote: "Our voices have power.
"Nike has joined in officially and contractually providing maternal protection to the female athletes they sponsor. This means that female athletes will no longer be financially penalised for having a child."
In a statement to Sports Illustrated, Nike said: "Female athletes and their representatives will begin receiving written confirmation reaffirming Nike's official pregnancy policy for elite athletes.
"In addition to our 2018 policy standardising our approach across all sports to ensure no female athlete is adversely impacted financially for pregnancy, the policy has now been expanded to cover 18 months."
BBC Sport has contacted Nike for comment.