Dina Lohan Says Pregnant Lindsay Lohan Is 'Already Showing' and 'Ready' to Become a First-Time Mom

Dina Lohan is bursting with pride at her daughter Lindsay Lohan's pregnancy news.

The mother of four gushed about Lindsay's exciting next chapter to PEOPLE on Wednesday, the day after the actress, 36, announced that she and husband Bader Shammas are expecting their first baby together.

"I'm literally over the moon. I'm so happy, I can't stop smiling," says Dina, 60. "It's incredible. We're just so excited. It's just such a beautiful thing for my child! And I love babies. Who doesn't?"

"My oldest baby is having a baby," added Dina. "It's so crazy. I'm in disbelief a little bit sometimes because you're like, 'Well... it makes you older clearly!' "

RELATED: Lindsay Lohan Is Pregnant, Expecting First Baby with Husband Bader Shammas: 'Blessed and Excited'

Jamie McCarthy/Getty Images Lindsay Lohan and mom Dina Lohan

This will be Dina's second grandchild. Her son Michael Lohan Jr., 35, and his wife Nina Ginsberg share one child together, daughter Isabel Scarlet — born in June 2021.

According to Dina, Lindsay has long wanted to be a mom. "Lindsay has always loved kids because I love kids and my mother loves kids; I'm one of four," Dina says. "We have a big family, so she's always wanted children. And she's so maternal. Isabelle, her niece just runs to her when she sees her."

The timing, Dina says, is "perfect" for Lindsay and her husband. "She's been trying and then it happened, that little stick came up positive," explains Dina. "It's the right time for her and Bader is an angel. Her husband is so sweet and they're just so happy. They're just really happy and ready."

"He's so happy," Dina noted, of Shammas.

Lindsay Lohan/Instagram Lindsay Lohan and Bader Shammas

Sources have told PEOPLE that Lindsay is due this summer.

While Dina would not confirm a due date ("I cannot tell, I will be in trouble!"), she did tell PEOPLE her daughter is already showing.

Dina also stayed mum on whether Lindsay was having a boy or girl, but says she does know what the baby's sex will be. "The nursery's all white, so that gives you nothing," Dina jokes.

Lindsay and Shammas, 36, live in Dubai, though Dina says she's in constant communication with her daughter. "She's like, 'Mommy, what does this mean? I feel like this. What is this?' " Dina says. "We do that every day, every morning. 'How are you feeling?' "

The two are also in a group chat alongside Dina's daughter Aliana Lohan and sons Michael and Dakota Lohan. "They text every day, like 10 times a day," Dina says. "It's so funny. Two of them will be talking and then someone else will be talking. And I'm the mom, so I try not to get involved in whatever's happening."

As for the birth plan, Dina also didn't reveal much but insists she'll be by Lindsay's side. "I will be there," she tells PEOPLE. "Absolutely. I'll be there for sure."

Pixie Productions Dina Lohan and daughter Lindsay Lohan

RELATED: Paris Hilton Says Pregnant Lindsay Lohan Should 'Soak in Every Moment': 'It's Just So Precious'

Lindsay announced she's expecting her first baby with a sweet post on Instagram Tuesday.

Alongside a photo of a white onesie reading "coming soon," the Parent Trap star wrote, "We are blessed and excited! 🙏🤍👶🍼," and tagged financier Shammas in the post.

Commenting on the post, Dina said she is "over the moon" at the news that her daughter is going to be a mom. "Filled with so much JOY and happiness ❤️❤️," she wrote in the comments section.

Lindsay's longtime pal Paris Hilton, who welcomed a baby boy named Phoenix Barron in January, was also among those sharing their well wishes. "Congratulations love! So happy for you 🥹 Welcome to the Mommy Club!🥰," wrote Hilton, 42.

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And many of Lindsay's 12.5 million followers couldn't help but reference the famous "I'm not like a regular mom, I'm a cool mom" quote from her 2004 hit teen comedy Mean Girls in the comments.

"You'll definitely be a cool mom. Congrats 💜💜💜," wrote one while another said, "That's so fetch. She's not a regular mom, she's a 'cool mom.' "