Katharine McPhee Says Son Rennie Is 'Much Bigger Baby Than His Peers': 'Ahead of the Curve'

Katharine McPhee
Katharine McPhee

Amy Sussman/Getty Images

Katharine McPhee Foster loves watching her baby boy grow up right before her eyes.

The new mom shares 5-month-old son Rennie David with husband David Foster, and speaking with PEOPLE on Friday, she says their child continues to be "advanced" in how quickly he's hitting developmental milestones.

"His little teeth popped out and it's fun because they popped up earlier than when they were supposed to. He's a much bigger baby than his peers, so it's kind of fun to have a baby who is growing so well," McPhee Foster tells PEOPLE during the beach clean-up event with World Surf League Pure and Wildcoast, hosted by Shiseido Blue Project and actor Adrian Grenier at Zuma Beach in Malibu, California.

"It all evens out," she adds. "They all end up in the same place, but right now he's a little bit ahead of the curve. It's super fun to be like 'Oh, he's advanced.' But really you know that your baby is just the same as any other baby."

The Country Comfort star says "nothing has surprised me" about motherhood, and she wants future moms to know that it's a joyful experience to welcome a child.

"You get all the opinions from people, and your life is going to change and you're going to be tired, and yeah those things happen. My life has changed, but not really," says McPhee Foster. "What I mean by that is that it just feels like he was always here. My life has changed because I'm so much happier."

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"Sometimes you hear more negative stories about motherhood and how tired you're going to be and it's so hard. I'd like to be an example of how great it is and how positive it is," she continues. "Because you do hear those things, but I think they sometimes get clouded with how hard it can be."

"And it is hard," she says, "but my attitude towards being a mom is just so grateful. It comes from such a grateful standpoint that I think when you come from a place of gratitude, the things that are hard you just deal with them and you move on. The joy outweighs the struggle."

Becoming a parent did alter her perspective on the environment and building a sustainable, healthy future for future generations. That's why she felt it was important to be involved with the initiative to clean local beaches.

katharine mcphee
katharine mcphee

Amy Sussman/Getty Images

Now as a mom, she says she thinks of questions like, "'What's it going to be like in 10 years? Are we going to get our act together? Are we going to clean it up? Is it going to turn into something quite different than what I remember? What is he going to grow up in?' "

"I'm raising [Rennie] in Los Angeles and I've really noticed L.A. take a huge nosedive in terms of its cleanliness. We're having a huge problem here and it's such a daunting subject. I don't even know where to begin," she tells PEOPLE.

"And it's all connected. The trash makes its way here. It makes its way to the ocean and to the beach. It's very upsetting. I don't know what the answer is, but we have to have everyone on a daily basis doing what they can be responsible for."