SINGAPORE — Chinese 12-year-old Yu Zidi has won a bronze medal at the swim world championships, an astounding feat for a girl who would be a sixth or seventh grade student depending on the school system.

Yu earned the medal by swimming in the prelims of China’s 4×200-meter freestyle relay team. She did not swim in the final on Thursday — China placed third behind winning Australia and the United States — but gets a bronze medal as a team member.

She has been close to winning an individual medal, placing fourth in both the 200 butterfly and the 200 individual medley. She still has the 400 IM to swim.

Brent Nowicki, the executive director of World Aquatics, said the governing body would look at its age-limit rules. The limit is now 14, but athletes can reach the worlds if they surpass a tough time standard.

“I didn’t think I’d have this conversation, but now I think we have to go back and say is this appropriate?” he said this week in Singapore. “Is this really the right way to go forward and do we need to do other things? Put other guardrails up? Do we allow it under certain conditions? I don’t know the answer.”

He called Yu “great.” He also said officials had to be “careful” about the age issue.

Friday’s session will be missing the two big stars of the meet so far: France’s Leon Marchand and Summer McIntosh of Canada. Both have no final swims.

Five finals were set for Friday. Some of the attention will go to Evgeniia Chikunova, swimming as a Neutral Athlete. She holds the world record in the 200 breaststroke where she has the top time entering the final. The top challenger is American Kate Douglass.

South African Pieter Coetze is the favorite in the men’s 200 backstroke. Yohann Ndoye-Brouard of France and Hubert Kos of Hungary were the next quickest qualifiers.

The other finals are in the women’s 100 free, the men’s 200 breaststroke and the men’s 4×200 relay.