Being pregnant for the first time can be scary — How, exactly does the baby fit through there? — even for someone as badass as Serena Williams. In an interview with POPSUGAR, Serena admitted, "I was terrified to push a baby out," so it's no surprise that now she's on the other side as a mom [1] to her beautiful daughter Alexis Olympia, that she has some sage advice for other moms who are pregnant — namely, her friend Meghan Markle [2], Duchess of Sussex.

It was announced in October that Meghan is expecting her first child with Prince Harry [3], and even though Meghan's the one expecting, Serena says that Meghan "still gives me more advice," which prompted Serena to give the Duchess some guidance [4].

After speaking to Meghan recently, Serena recalled to People how the pair's conversation started: "I'm like, 'How are you?' and she's like, 'No, how are you?' and I'm like, 'You're so sweet, but I'm really asking – how are YOU?' I'm like, 'Meghan, stop being so nice . . . you're the pregnant one, aren't you supposed to have hormones, why are you so sweet?' But that's always been her."

However, with such a huge milestone coming for Meghan, Serena shared a nugget of advice for first-time moms — beyond ceasing to be "so nice" — that honestly, everyone could use, pregnant or not: "It will come."

"I don't know what's going to happen, I didn't know how [I was] going to have a baby, and it all came," Serena said. "It's so crazy, I totally changed, and it literally is like a switch. And so, I say that, 'It will come.'"