The 38-year-old star is three and a half months pregnant and sharing her news in Hello! magazine, she said: ''This pregnancy has brought us a joy we never knew existed."
It will be her first child with her husband of almost two years, singer-songwriter Jack McManus.
Former EastEnders star McCutcheon told last year how she had fought a secret seven-year battle with the chronic fatigue syndrome ME, which led to severe depression.
She told Hello!: ''We'd always said that if we were fortunate to be blessed with a child, that would be wonderful, but we were very aware that it's not a given.
''As a woman in her late 30s who's experienced health problems, I thought I might have to accept that it wasn't a path my life was going to take, but it would have been a great sadness in our lives if that had been the case.''
Her child is due on Valentine's Day next year and has given her back some joy after last year being declared bankrupt, as a result of her illness leaving her unable to work.
''It was a terrible time in our lives,'' she said. ''But you discover who your friends are and we found amazing support from people who really came through for us.
''It's like finally the tides have turned. Great things are starting to happen on the work front, but more than anything, expecting our baby boy has given us clarity about what matters."
:: The full interview is in the new edition of Hello! magazine which is on sale now.