One common theme is the characters' reactions to the pregnancy. For example, if Penny were to get pregnant, Leonard's response would be a big part of the story. Another theme is how the pregnancy affects the group's dynamic. The friends might start acting differently towards the pregnant character.
One possible fanfiction could be about how Bernadette adjusts to her pregnancy while still trying to keep up with her demanding job. Maybe she has to deal with morning sickness at work and tries to hide it from her colleagues at first.
One popular 'Big Bang Theory' pregnant fanfiction might be those that explore Penny getting pregnant. Some fanfics could focus on how the group dynamic changes with a new addition on the way. However, it can be a bit hard to specifically recommend one as there are many out there. You can try searching on fanfiction - specific websites like Archive of Our Own.
There might be a fanfiction where Penny is pregnant and she starts to feel really isolated because she's the only one in the group going through this. She misses her old life a bit, and the story could be about how she overcomes these feelings with the support of her friends and Leonard. It's very emotional as it deals with her internal struggles.
The Big Bang theory is the prevailing cosmological model for the universe. It states that the universe began as an extremely hot and dense point, and then it has been expanding ever since. Evidence for this includes the cosmic microwave background radiation and the redshift of galaxies.
One possible fanfic could be about how Bernadette's pregnancy affects her relationship with Howard. For example, Howard might become overly protective, leading to some comical misunderstandings. They could also have different ideas about how to prepare for the baby, like Howard wanting a high - tech nursery while Bernadette is more practical.
There are many possible fanfictions on this topic. One could imagine that in the fanfiction, Penny's pregnancy might bring a new dynamic to her relationship with Leonard. For example, they could become more protective of each other and start planning for their future as parents more seriously. It might also affect their friendships with Sheldon and the others. Sheldon, who is not always good with changes, might initially struggle to adapt to Penny being pregnant and the new baby in their lives.
There could be a fanfiction where Penny's pregnancy makes Leonard super nervous. He starts freaking out about being a dad and all the responsibilities. Meanwhile, the rest of the gang tries to support them in their own clumsy ways. It's interesting to see how the characters' relationships develop during this big life change.
The plot could focus on the couple's fears and hopes. For instance, they might be worried about being good parents. Howard could be afraid he'll be like his own father, who wasn't always around. Bernadette might worry about balancing her career and motherhood. The story could show them working through these fears together, like attending parenting classes.