Now in its seventh season, Game of Thrones is not playing around when it comes to plot, as evidenced by Cersei's big confession to her brother Jaime in Episode 5. But, just to play devil's advocate, have we even considered if Cersei is really pregnant on Game of Thrones? If so, maybe her plans for a dynasty weren't as ridiculous as I originally thought. Cersei is in quite a pickle right now, and she needs her brother more than ever. If Jaime believes he's about to be a father once again, it could be exactly the motivation he needs to stay loyal to an increasingly loony tunes Cersei. Which is why I'm a little suspicious of this new development.
For a little bit of backstory, Cersei was told as a child by a prophet, called Maggy the Frog that she would have three children, and that all three would die. So far, she's been completely right. If Cersei were to have another child, it would somehow mean that Magy the frog was wrong. If this prophecy is indeed incorrect, then that kind of calls into question every prophecy made on the show, including the one about Azor Ahai/Prince that was Promised, meaning that Jon and Daenerys's destinies may not be as set in stone as originally thought. I tend to think that this won't happen.
Cersei tells Jaime she's pregnant right as he is trying to convince her to work with Daenerys, what with the dragons and the army of the dead coming for them. Instead, Cersei says that she's pregnant, and that her dear brother is the father. Again. Obviously, Jaime responds by getting all emotional. Somehow, I feel like this is a Cersei trick. This is a trick, right?
If you can remember all the way back to Season 3, you'll remember Olenna Tyrell and Tywin Lannister argue about who was going to marry who. Tywin wanted Loras Tyrell (RIP) to marry Cersei, while Olenna argued that Cersei was just about at that point where she was too old to have children anymore. Of course, this certainly doesn't mean that it's impossible for Cersei to get pregnant, Olenna's not a Westerosi OB/GYN, but it is another factor to consider.
Then again, perhaps Cersei really is pregnant. If that is the case, then Westeros could be dealing with another Joffrey on their hands. Perhaps she'll lose the child. Perhaps Dany and Jon will take her throne and she and her kid will move to Volantis. But for now, it's definitely upped the stakes. For Jaime at least.