We already know pregnant women are basically pro athletes, but one mother-to-be has proven herself a true hero — by saving a boy from drowning.

Stephanie Swedberg, who is 33 weeks pregnant, was teaching her 3-year-old twin boys how to float on Sunday at Crystal Beach Park in her hometown of Burnsville, Minnesota.

Swedberg, a former lifeguard, tells Fox 9, “I’ve just known with these guys that I wanted them to learn how to swim as soon as possible.”

She was splashing with her twins and her sister around 11 a.m. when she heard the cries of another mother. About 20 feet away, a group of boys ages 10 to 14 were swimming in deeper water.

“I didn’t really realize anything was off until I saw one of the moms fully dressed, sprinting into the water and screaming for somebody to help her son,” Swedberg tells Fox 9. “Then I looked over and I saw one of the boys unable to keep his head above the water.”

She asked her sister to watch her twins, then swam toward the terrifying scene.

Swedberg says this is the first time she’s ever had to rescue someone. She credits the eagle-eyed mom who spotted her distressed son in time, but warns of how quietly drowning can happen.

“He wasn’t screaming,” she says of the struggling boy, who, she later learned, had not had much swim instruction. “He was just thrashing around, bobbing a little bit.”

Emphasizing the importance of swimming skills, she adds, “I encouraged him to keep taking swimming lessons and maybe become a lifeguard [himself].”