Catherine, 31, who plays Rover's Return barmaid Eva Price, announced in August that she is pregnant with her first baby with her fiancé, 27-year-old fitness trainer Tom Pitfield.
She revealed that her due date is in March 2015, but has not yet commented on the baby's gender.
However, some of her friends have been more forthcoming. Financial Times analysis editor Christopher Grimes sent Catherine a tweet saying: "nice seeing you and the bump. I fully expect him to be on Broadway by the time he is 3 haha"
@Cath_Tyldesley nice seeing you and the bump. I fully expect him to be on Broadway by the time he is 3 haha
- Chris Grimes (@Chris_Grimes) October 11, 2014
A couple of Tom's friends also congratulated the pair on his Facebook page.
"Seriously!!! You guys are too cute. Congrats on the lil man x" wrote one.
Another added: "Really pleased for you both. Another boy in the family! X"
Catherine is one of three Corrie girls to fall pregnant at the same time, leaving show bosses with a maternity headache as she and Jennie McAlpine, 30, who plays Fiz Stape and Paula Lane, 28, Kylie Platt, are all currently expecting their first babies.
However, Catherine will have eased her bosses' minds slightly as she has confirmed to fans on Twitter that she'll be returning to Corrie after her maternity leave.
- Catherine Tyldesley (@Cath_Tyldesley) October 11, 2014
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