Speaking on The Paul O'Grady Show, the actress confirmed that the ordeal contributed to her decision to quit playing DI Sam Nixon after seven years on the ITV1 police drama.
"I'll be absolutely honest with you, I had two miscarriages - one in January and one in July," Maxwell, 45, explained.
"It was a really sad time for me and now I don't mind talking about it. It's not like a secret. In some ways I feel the more I talk about it, the better it is - because I kept it a secret at the time."
Confirming that she returned to work shortly after the first baby loss, the star continued: "In some ways I think it was easier to be Sam than be Lisa. [I was] facing up to a lot of stuff and I just ignored the first one. I thought it was my last chance to [have] a child again - and I was quite kinda down about it but I soldiered on.
"[I] ignored it, like I do everything, and then I was lucky enough to fall pregnant again four months later - and then the same thing happened."
Maxwell, who already has a nine-year-old daughter named Beau, eventually took time off from the show on the advice of her co-star Roberta Taylor (Gina Gold). She then announced her decision to leave the programme in January this year.
She revealed: "This is the first Easter holiday [that I've been off]. For the whole holiday I've been with my kid."
The star's character is expected to be part of an "explosive storyline" before her on-screen departure in September.