ABC’s Once Upon a Time will make a very special delivery this Sunday at 8/7c, as Mary Margaret aka Snow White gives birth to a baby that the Wicked Witch is hot to get her green mitts on. With an eye on the imminent addition to the Charming clan, TVLine invited Ginnifer Goodwin — whose baby with husband/costar Josh Dallas should soon arrive with a bit less drama — to preview Season 3’s final three hours, including the top-secret scene that sets the stage for Season 4.

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TVLINE | I probably should know the answer to this, but I’ve never bothered to ask you myself: Which pregnancy came first? Would [series creators] Adam [Horowitz] and Eddy [Kitsis] have made Snow White pregnant regardless?

It’s something that we had sort of discussed over the past year-and-a-half. They knew that there was an “Untitled Ginny Goodwin/Josh Dallas Project” in the works, and we knew there was a very much-titled Snow White/Prince Charming Project in the works, and we were hoping that the timing would overlap. And they had given themselves some wiggle room in the writing. We knew that the characters wanted to become pregnant, so once we became pregnant in real life, they could say, “All right, here we go.”

TVLINE | But once they did write it in, did they give you a heads-up that Snow’s pregnancy would not be without drama?

Well, we knew that from the beginning! [Laughs] But what was lovely – and unexpected, just because no one thinks of these things that far enough in advance – is they found a way to help me be an extremely pregnant woman while filming. I was not asked to leap off any cliffs or things like that myself, once we knew there really was a baby in there.

TVLINE | I think back to a couple of episodes ago, where Snow was kicking back in the apartment, her feet up on a hassock….

Oh yes. One of my assistant directors actually got for me — and carried around the woods — a leather lounge chair. It went everywhere with us, including on mountaintops.

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TVLINE | When I visited the set in February, you and Jennifer Morrison used the word “creepy” to describe the Season 3B storyline. And really, what’s creepier than having the Big Bad going after a baby?

Absolutely. There’s something very Rosemary’s Baby about the whole thing to us, and I feel like that was almost honored in the wardrobe choices for Mary Margaret — though no one ever confirmed that that was any kind of inspiration. But all of those baby doll dresses of the ’60s eras kind of gave us an additional layer of the creeps.

TVLINE | Going into this Sunday’s episode, “Kansas,” Snow is in labor. Are she and Charming going to be able to lose themselves at all in the joy of childbirth?

No, that wouldn’t be near dramatic enough. [Laughs] We’re going to be looking over our shoulders the entire time, because we know that Zelena is after our newborn, in order to turn back time and change her destiny and possibly erase Regina from existence. We are not even going to get through the actual pushing part without there being complications that are not medically related.

TVLINE | One of our readers wondered: “Why not deliver the baby at the apartment, which has the protection spell?”

That’s a good point. I kept raising the question, “Why is Charming all right with Dr. Whale down there between Mary Margaret’s legs?” After all they’ve been through. [Laughs]

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TVLINE | Without revealing anything, will Baby Charming’s name make a certain amount of sense?

Yes, the baby’s name is going to be significant, absolutely significant. In fact, every time I not only read the script but then every time we filmed it, I got very, genuinely emotional. It was an excellent move — and very unexpected.

TVLINE | Might you and Josh steal the name?

[Laughs] You know what — the number of people who’ve stopped me on the street and said, “If it’s a girl, are you going to name it Emma? If it’s a boy, will you name him Henry?” is really staggering. I have to say it’s not something we are considering for real life, because we have to keep real life sacred. But it’s really funny to me.

TVLINE | You’ve always relished exploring the family dynamic with Snow, Charming and Emma. Have you thus appreciated what they did along those lines this season? Because they’ve had some very nice moments.

Yes. Though I don’t know what’s in store for next season — except that we’ll be thrown all kinds of curveballs – I hope that bringing another child into our family is going to pave the way for even more of those moments, because they’re always my favorite. I like our “heart-to-hearts on logs” far more than I do any of the swashbuckling.

CLICK TO PAGE 2 FOR GOODWIN’S THOUGHTS ON THE SPLIT SEASON, A HUGE SECRET SHE HAD TO KEEP AND SEASON 3’S FINAL TWIST