When the pregnant teenager is interviewed for a place on a veterinary course at university, she considers having an abortion so that she can focus solely on her education.
Sinead's stepmum Diane and boyfriend Bart McQueen are keen to change her mind, but will she listen to them?
Digital Spy recently caught up with Stephanie Davis, who plays Sinead, to hear about the pregnancy storyline and her character's role in the Esther bullying plot.
What has Sinead's pregnancy storyline been like to film so far?
"I've really enjoyed it. It's a really complicated situation for Sinead, but it's good fun for me at the moment. It's also going to get a lot bigger in the next few weeks.
"The pregnancy came as a huge shock to Sinead. Obviously she knew that she'd had a one-night stand, and I think she just knew straight away that the baby isn't Bart's. She's been completely thrown by it and she wasn't really ready to tell anyone, but then Diane went and told the McQueens straight away!"
How is Sinead feeling now that a couple of weeks have passed?
"I think Sinead is feeling more scared now, because she doesn't want anyone to find out the truth about the baby. The audience have now seen Sinead picking up the picture of Rhys from Jacqui's room, so now you know what she's hiding. It's a tough time for Sinead at the moment - she's lost her best mates, she's pregnant and she knows that Bart is not the dad."
The pregnancy plot comes to a head next week. What can you tell us about that?
"Sinead has an interview for a veterinary course at university, which is something she really wants to do. She really wants to get this because it's everything she's always wanted, but she's also got a big weight on her shoulders because of the baby.
"You'll see that Sinead is trying to block things out, but when the interviewer asks whether there's anything that would hold her back, she's pretty scared but says it'll be fine.
"Secretly she's planning to get rid of the baby at this point. Sinead thinks that if she keeps the baby there'll be too many complications, but if she has an abortion, all of her problems would be erased."
Do you think Sinead could be a good mum if she gave herself the chance?
"I think Sinead could be a good mum, but the problem is that she'd have to live a lie. She's in a relationship with Bart McQueen and it's Jacqui McQueen's fella Rhys who is the father, and he's just died. It's really awkward because the two families are intertwined. I think Sinead would be really scared if Jacqui found out, because she knows that Jacqui would kill her.
"With all of this running through her mind, Sinead turns up at the abortion clinic, but Diane finds out what she's planning to do at the last minute and rushes off with Bart to find her. They catch her just as she's about to go in, and they try to talk her out of having the abortion.
"Bart tells Sinead how much he loves her and how everything will be okay. I think Sinead then starts believing it herself - it's as if she blocks out that Rhys is the dad! But you'll have to wait and see whether she goes in for the abortion or not."
Long-term viewers will know that Diane can get slightly crazy when it comes to babies. Does she have Sinead's best interests at heart this time?
"I think at the moment Diane is definitely thinking of Sinead and she just wants what's best for her daughter. Diane knows that Sinead wants to be a vet, but she promises that she'd be around to help her. At the same time, Bart is saying, 'Why can't you keep the baby? It's ours and we're happy together'. So Sinead has all of these different opinions and options running through her mind."
If Sinead did keep the baby, do you think you'd enjoy playing a pregnant character and wearing a baby bump?
"If Sinead did keep the baby, I do think it'd be fun to play a pregnant lady. It'd be strange as well, because she's so young and wearing a baby bump would be really weird! I think it'd be a better storyline if she did keep the baby, because there's lots more places it could go."
Is Sinead and Bart's relationship strong enough to survive this drama?
"I hope it's strong enough. Sinead has been with Bart for a long time, she's always been honest with him and she loves him to pieces. I think knowing that Bart isn't the dad would kill her, so if she does keep the baby, I don't think she'd be able to keep up the lie for very long.
"She'd try to pretend that Bart was the dad and keep up the lie for a little while, but the truth always comes out in the end, doesn't it?"
It's fair to say that your character has been controversial recently with Esther's bullying storyline! How have you felt about exploring Sinead's nastier side?
"To be honest, it's a great storyline and really fun to play, so when I go on set, I can't wait to do it. But then on the other hand, Jazz who plays Esther is one of my best friends at Hollyoaks. With some of the vile stuff Sinead has been doing recently, at the end of the scene I've had to go up to Jazz, give her a hug and say, 'I'm sorry, I love you, I don't mean it!'
"We did this one scene and Jazz was actually crying afterwards. It's horrible, but it's so good to play. I also worry because you get people who think it's real. I always worry I'm going to get stoned in the street for being so horrible!"
What is it about Esther that Sinead dislikes so much?
"I think Sinead was mainly led on by Maddie, who brainwashed the group to think that Esther was a bit of an outsider. Now that Maddie has died, Sinead is preoccupied with everything that's going on in her own life with the pregnancy and the baby being Rhys's, so I think the bullying is a way to take it out on someone. She takes it out on Esther because Esther is vulnerable.
"Sinead also blames Esther for the whole crash now. She loves Bart too much to blame it on him, so she automatically thinks it's Esther's fault. It's almost like she's starting to believe her own lies and she does genuinely think that Esther is a horrible person."
Do you think Sinead will be redeemed in the long-term and the viewers will like her again?
"Not yet I don't think, there's a long way to go! Maybe they will in the end, but I'm not sure if people will ever fully forgive Sinead again. I think I'm just going to be hated, and it's all going to go downhill from here! I've already started getting abuse on Twitter and I've had to say, 'No it's not real!' I'll have to tweet some more pictures of me and Jazz smiling!"
Were you sad to say goodbye to the cast members who left the show in the crash episodes?
"I was! Andrew Moss who played Rhys is the life and soul of the party. He was such a joy to have in work every day. It's weird, because we'd all become such a tight group and everyone was settled. I hate change, so I don't like it when people go!
"I miss them all loads, because they were our little group. Scarlett Bowman, Dylan Llewellyn and Tosin Cole were filming with us 12 hours a day, every day! They were more like family but we'll still see each other. I know they're all going to go on and do well in other stuff. I know they're all doing really well actually, so I'm really pleased for them."
> Read the latest 'Hollyoaks' spoilers and news
Hollyoaks airs weeknights at 6.30pm on Channel 4, with first look screenings at 7pm on E4.