Breanna Stewart, Marta Xargay Casademont on 'Easy Decision' to Welcome Daughter Ruby via Surrogate

When Seattle Storm star Breanna Stewart suffered an Achilles injury in 2018, she made a plan.

The then-24-year-old power forward, known affectionately to fans as "Stewie," didn't know when she'd get time off the court again.

"'If I'm gonna be out, this is probably the best time to do it,' " Stewart, now 26, tells PEOPLE she thought to herself of freezing her eggs. "Then after I did it, I was like, 'This is probably one of the best decisions I've ever made.' "

Two years later, Stewart's former Russian Premier League teammate Marta Xargay Casademont had become her wife. Using Stewart's frozen eggs, they welcomed their daughter Ruby Mae Stewart Xargay via surrogate on Aug. 9, they first shared exclusively with PEOPLE.

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"It was an easy decision," Xargay Casademont, 30, says of using a surrogate. The former pro basketball player, who played for the Phoenix Mercury and in the 2016 Olympics for her home country of Spain, is now retired.

Stewart "wasn't going to get pregnant while she was playing," Xargay Casademont says. "And I wasn't ready to be pregnant by then, when we wanted to start the process."

So, while they were hunkered down in the WNBA bubble in 2020, they started looking into surrogacy.

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In the time since, Stewart has won the WNBA Championship with the Storm, the distinction of WNBA Finals' MVP and an Olympic gold medal with the U.S. women's basketball team.

Now, life with a 2-week-old baby is still surreal for the new moms, who wed in an intimate ceremony on their condo's rooftop in July.

"I have these moments that I'm like, 'I can't believe we're parents,' " Stewart says from the road with her team as they finish out the 2021 season. "I think we're great parents, but it's still like, wow. A whole person."

"I could be, like, 24 hours looking at her and staring at her," gushes Xargay Casademont from their home in Seattle. "Just the joy that she already brings to us, the happiness, it's amazing."

Xargay Casademont froze her eggs in June, and she and Stewart are looking forward to expanding their family – but "not right now!"

"We're pretty busy," Xargay Casademont says. "But we want to have a family, a big one."

Adds Stewart, "[Egg freezing] is something that a lot of people should do, especially our generation. We're so focused on being successful and doing all these things, that sometimes you forget about planning for beyond."

RELATED: Breanna Stewart, Wife Marta Xargay Casademont Welcome First Baby, Daughter Ruby: 'Best Moments'

For the couple, planning for a family also included talking about their finances — and figuring out how they'd share them.

They've partnered with Ally Financial to encourage all couples to be open and honest about money. The company offers a free, interactive financial vow generator to help people open up to their partners about where they stand financially in a fun, low-pressure way.

On one of their first dates, Stewart and Xargay Casademont started having "lighthearted conversations" about their respective investments, financial advisors and properties in the U.S. and Spain.

"We weren't afraid to talk about money," says Stewart. "This is your person, and your person for life, and you need to have that conversation."

Back in April, with a baby on the way, they opened a joint account for shared expenses, while they each kept some money separately. "Especially in the basketball world, and probably the sports world, that's probably the thing that you see most," Stewart says. "You have two successful people, and instead of putting it all together, you can put a lot of it together, and still keep some separate."