"Everyone at work keeps going, 'God, you're pregnant again?'" Capshaw tells PEOPLE."Because I really was pregnant last year! It does seem a bit, like, 'What? How are you pregnant again?' Yet, here I am!"

By peoplestaff225
Updated March 21, 2012 06:00 PM

Jessica Capshaw‘s Grey’s Anatomy castmates are feeling a sense of déjà vu with their costar.

“Everyone at work keeps going, ‘God, you’re pregnant again?'” the actress, who is expecting her third child in June, tells PEOPLE.

“Because I really was pregnant last year! It does seem a bit, like, ‘What? How are you pregnant again?’ Yet, here I am! I feel so lucky to be pregnant for a third time.”

Capshaw, 35, purposely put some distance between Luke Hudson, 4½, and Eve Augusta, 17 months. Eve and her new sibling (the actress and husband Christopher Gavigan are not finding out the sex of the baby) will be much closer in age, and Capshaw hopes that will give her two younger children a special bond.

“Luke will be very hard-pressed to remember a time before Eve, but if he really, really tried, he could,” Capshaw says. “Eve will never remember a time before this baby. I think there’s something so lovely about that.”

Capshaw has also been hearing from friends with three children that the third brings a special chaos to life at home — but the actress is doing all she can not to anticipate the worst.

“I don’t really think about what the challenges are going to be,” she says. “For me, it’s not about the challenges. I keep thinking about how lucky we are. For some reason, even with the third one, it really is never, ever lost on me that every single baby is a miracle.”

To protect her little miracles, Capshaw — along with Julianne Moore, Christina Applegate and Maya Rudolph — recently joined Moms Clean Air Force to call on legislators to protect a historic ruling that would limit toxic pollution from mercury and other damaging chemicals emitted by power plants.

After the Mercury and Air Toxics Standards ruling passed in February, opponents in the Senate began an appeal process to kill the ruling.

“It’s not only frustrating, it’s maddening,” Capshaw says. “It’s not okay for there to not be restrictions on the toxins that are released into the air that we breathe.”

“Water and air are pretty elemental to our lives,” she continues. “When either one is being compromised or contaminated or not being taken care of as the precious resource that it is, we have to collectively figure out who’s in control and who can do something to make sure that it is valued.”

— Helin Jung