The barmaid is now carrying a baby for Gary Windass and Izzy Armstrong, but when the pregnancy begins to have an adverse effect on her health, Tina's boyfriend Tommy Duckworth (Chris Fountain) urges her to have an abortion.
Tina instantly dismisses the suggestion but is later given food for thought during a candid heart-to-heart with Izzy. What will Tina decide to do?
Digital Spy recently caught up with Michelle Keegan, who plays Tina, to hear more about the latest twists to the tale.
What has Tina's surrogacy storyline been like to film so far?
"It's been really good and really eventful! I'm very grateful to have been given this storyline because it's such a big one and we've already seen lots of twists and turns in it. It's been really interesting to film."
We've heard that you recently had a meeting with a real-life surrogate mum, Jo Anderson, to discuss the storyline. Did that help with your research?
"It did 100%. Jo is a mum-of-three who's been a surrogate mother twice. She was lovely, and she explained the difference between her being a surrogate and her being a mum. I wasn't sure whether you would become attached to the baby or not, although in the storyline we've been saying that Tina isn't attached as she's doing it purely for money and to help Gary and Izzy.
"When I spoke to Jo, she told me that she felt totally detached from the baby - she knew the child wasn't hers and she was doing it as a favour, so that's the way she saw it. So that's the way I'm going to play it as Tina now, too.
"Jo also said that when she was pregnant with her own children, she found herself rubbing her bump, but when she was a surrogate mum carrying the other children, she didn't really touch her bump. It was really interesting to hear the little differences like that."
In next week's episodes, the pregnancy seems to be taking its toll on Tina and she faints. What can you tell us about that?
"I don't think Tina realised the impact that pregnancy was going to have on her body, and I don't think Tommy did either. She feels sick and she faints, and that's when she has to get checked over by the doctor.
"Tommy doesn't react well to this at all, as he's really worried. As far as Tommy is concerned, if this pregnancy is affecting Tina's health then something has to be done. He thinks there's not enough money in the world to make it worth putting your health at risk."
How does Tina feel when Tommy then urges her to have an abortion?
"Well, she doesn't like to be pressurised - not at all! When Tommy suggests it, she just thinks that abortion isn't an option."
How do Izzy and Gary react to Tommy's latest interference?
"Obviously they're not very happy. The fact that Tina is pregnant means that it's very late in the day to start having second thoughts. But you'll see that Tina and Izzy have a bit of a talk in the back room of The Rovers. Tina tells Izzy all about Tommy's frustrations and his problems with the surrogacy deal. Izzy actually understands, because the issue is with Tina's health. Izzy then says that she and Gary can just start again with someone else.
"That makes Tina question everything even more. She wonders how Tommy - someone she really loves - can be so quick to make demands, while Izzy is able to see it from someone else's point of view. Izzy says, 'If it's affecting your health, I'd rather you do whatever you want to do and we'll still be friends'. It's going to be a tough decision for Tina to make, whatever happens."
Next week's episodes also see the surrogacy deal become public knowledge on the street. Does Tina find that difficult to deal with?
"Well, obviously Tina didn't want anyone knowing the truth. She's not impressed at all, because it's Tommy who announces it when he loses his temper at The Rovers. At first it seems that Tina might find it difficult, but then she says that it's got nothing to do with anyone else.
"I think Tina has got her head screwed on and she's just concentrating on looking forward. She thinks this situation only concerns her, Tommy, Gary and Izzy, so she isn't interested in what other people say. Tina is quite a strong person and she doesn't let anyone else's opinion affect her decisions. It's a bit like water off a duck's back at the minute!"
Is there anyone in particular who gossips about it?
"Obviously Norris! He makes a few comments. Other people are speaking about it too, but I don't think Tina really cares."
Looking back, do you think Tina should have just accepted Rita's offer of a loan to clear Tommy's debts, rather than going ahead with the surrogacy?
"No, because then she'd be in debt with Rita! Because Rita is her friend, she doesn't want to owe her money. I think Tina just sees the surrogacy as her only option and her only way to start afresh.
"She's not just doing it for the money anymore, either. She's also doing it for Gary and Izzy now, because obviously she's struck up a bit of a relationship with them and the Windass family. She wants to help them out."
How do you feel about sharing so many scenes with Barbara Knox, who plays Rita?
"Oh God, I love it and I always have from day one. I've been working with Barbara for five years now and I always get really excited about it. I always know it's going to be a good scene with Barbara, and I really look up to her. She's a really nice lady and she's a really good friend as well."
After so many dramas, do you think Tina and Tommy can ever be a strong and united couple?
"Yeah, I hope so! I hope this can make them stronger, depending on what happens. Fingers crossed they'll stay together."
Tina also has some more scenes with David next week as they confide in each other over their respective relationship troubles. Is there still a spark between them?
"Well, I really love working with Jack who plays David - he's a bit like my comfort blanket because I originally came into the show as his girlfriend. I really miss having lots of scenes with him, so when I do work with him, I have a right laugh.
"As for whether there's still a spark between them, I don't know. They're really good friends because they grew up together and they've been through so much. It's hard to say whether there is still a spark between them or whether it's just a friendship. I'd like to say there's still a spark, because David is her first love."
Storylines are often planned really far in advance, so have Corrie told you how the surrogacy plot will end?
"No, not really. We've heard a few options of what might happen, but nothing is in concrete yet. It'll be just as much a surprise to us as it will be to the viewers!"
Is Tina going to be busy at Christmas this year?
"It's a quiet one for her this year as she's in The Rovers working! There's no big Christmas storyline for her this year, but I do get a scene on Christmas Day."
Will Tina get involved in Tyrone and Kirsty's domestic abuse storyline again?
"Not at the minute, but I know that Tina is going to get involved again further on down the line. Obviously Tyrone and Fiz are striking up a bit of a friendship again, and Tina is going to get involved in that storyline. So we'll see!"
> Read the latest 'Coronation Street' spoilers and news
Coronation Street airs Sunday, Wednesday and Friday next week on ITV1.