The actress appears alongside cast members including Alex Kingston and Anne Reid in the supernatural thriller, which follows the lives of three families who live in the same house in different time periods.
"I started to get used to my bump," she told The Sun. "It was very much part of my character. At the time I had two pregnant sisters. It was really helpful as I had these two great points of research."
The Mistresses star, who is dating actor Jonathan Kerrigan, added: "It made me quite broody, especially being around all those newborn babies."
Marchlands begins on February 3 at 9pm on ITV1.