In the picture, Swank is seen beaming while cradling her bump as she wears a black T-shirt with pumpkins printed on it, and her dog can also be seen making a cameo, wearing a black and orange matching pumpkin sweater.
Swank captioned: ”#HappyHalloween from me, Pumpkin Moon and my PumpTwins. #SetLife #HairAndMakeUpTrailer #AlaskaDaily.”
The Million Dollar Baby star is currently working on US drama Alaska Daily, playing journalist Eileen Fitzgerald.
Swank broke the news that she is expecting as she promoted the show on Good Morning America last month.
The actress excitedly said at the time: “This is something I have been wanting to share for a long time, the next thing is I am going to be a mom! And not just of one but of two!
“It’s so nice to be able to talk about it and share it, and I am sharing it right now for the first time. I am so excited!”
Following her live show announcement, Swank took to Instagram to post a photo of her pointing to her baby bump, as she captioned: “Coming soon…DOUBLE feature”.
Later that day, on Live with Kelly and Ryan, Swank confirmed that she is in her second trimester and shared how she felt her pregnancy was a “miracle”.
“I’m feeling great right now,” the Boys Don’t Cry actress said.
Speaking on how she’s found being pregnant on set, Swank added: “My clothes started not to fit so I had to, the other day... cut [my jeans] open. And then I put a jacket on that wasn’t in continuity.
“And [they] came and said, ‘That’s not in continuity.’ I said, ‘I’m going to make it work.”
Swank revealed that twins run in both her family and her husband Schneider’s, as she said: “It’s such a blessing. It’s a total miracle. It’s unbelievable.”