Tessa Rider needed something to relieve her pregnancy pain, and she knew a gentle swim at the local pool would help ease her discomfort. What she didn’t expect was that it would send her into labour.

The expecting mum and her partner Matthew Jones arrived at the YMCA in Colorado at 10.30am on a quiet Sunday morning, hoping the water would help Tessa’s hip pain. She floated on a pool noodle, enjoying the relief but it wasn’t long before she realised she was actually in labour.

“She looks at me and says, ‘We need to go,’” Matthew told TODAY Parents. “Tessa has barely made it out of the pool, she’s like two, three steps from the rail. She’s on all fours and she’s visibly in pain and also in the middle of the contraction.”

Matthew was planning to gather their belongings so they could head to the hospital, but it was too late. Tessa was crawling out of the pool, and she’d been spotted by 18-year-old lifeguard Natalie Lucas.

“I was like, ‘This doesn’t look great. Let me go over to see what’s happening,’” Natalie said. “I walk on over to them and they say, ‘We’re having the baby.’”

The teenager flew into action, getting medical gear and instructing someone to call an ambulance.

“I start trying to help in any way I can, trying to support her and make sure she’s comfortable,” Natalie explained. “They’re both staying extremely calm, which helps me because I’m shaking a little. But I know I need to help and make sure I’m there with them in any way I can because I’m the lifesaver.”

In just a matter of minutes, the baby was born into Matthews hands.

“The baby’s body comes out, along with a torrent of amniotic fluid from her water breaking as the baby comes out.”

With Tessa shaking and in pain, Natalie sat behind the new mum so she could h

“There’s a funny picture of me sitting back-to-back with her so she could put her weight on me to support her and give her some relaxation and calm,” Natalie said. “I was trying to help in any way I can.”

The baby boy, named Tobin or Toby for short, was crying and breathing as Natalie spoke to emergency services over the phone.

“We had to make sure his chest was rising and falling … I had to clean out the baby’s mouth to make sure the airway wasn’t blocked and that he had an open passage to continue breathing.”

Little Toby and Tessa were then taken to hospital, where they were given a clean bill of health.

“Contrary to the surrounding events of his birth, he is the most chill baby I ever had,” Matthew said.