Yes, there might be some out there. You can try searching on popular fanfiction websites like Archive of Our Own (AO3). They have a large collection of various fanfictions, and you may find some related to Jareth and Sarah in a pregnancy scenario.
The relationship might become more intense. With the pregnancy, they have to rely on each other more. Jareth may show his softer side as he takes care of Sarah, and Sarah might start to see him in a new light, beyond the intimidating Goblin King.
You could try specialized Labyrinth fanfiction forums. These are often filled with die - hard fans who might have written or know where to find 'Jareth x Sarah pregnant' fanfiction. Additionally, some Discord servers dedicated to Labyrinth fandom could also be a good source. You can ask around in these communities and see if anyone can point you in the right direction.
Perhaps the pregnancy is a result of some magical mishap. Sarah then has to deal with not only the physical changes but also the strange magical implications. Jareth could be trying to find a way to reverse it at first but then grows to accept it as their new reality, which would create a lot of drama and character development.
Love in this fanfiction could be shown as a force that gives them the strength to face the unknown. The pregnancy is full of uncertainties, like what the baby will be like, how they will raise it between two worlds. But their love for each other and the baby gives them the courage to face all these questions. They support each other emotionally, and their love becomes the foundation for building a family, despite all the odds against them.
In the fanfiction, the pregnancy could be a symbol of a new beginning for the relationship between Jareth and Sarah. It forces them to re - evaluate their feelings for each other. Sarah might become more empathetic towards Jareth's loneliness in his magical world, and Jareth could start to understand the importance of human emotions. They could embark on a journey to find a safe place for their baby to be born, facing various challenges along the way that test their love and commitment.
There could be some out there, but a lot of fanfiction platforms have rules against explicit content. You might have better luck looking for more general Jareth and Sarah fanfiction on Archive of Our Own (AO3). It has a large collection, and you can filter by different themes and ratings to find something that suits your taste, but stay away from inappropriate stuff.
They are a popular pairing because of the strong dynamic between them in the original story. Dark Jareth is a mysterious and powerful character, and Sarah is a brave girl. The contrast makes for an interesting relationship in fanfiction.
The kiss can also be seen as a moment of temptation. Jareth, being the Goblin King, has an allure about him. In fanfiction, the kiss might be his way of trying to keep Sarah in the Labyrinth on a more permanent basis. It could be part of his strategy to make her forget about her quest to rescue her baby brother. However, Sarah's reaction to the kiss varies in different fanfictions. Sometimes she is initially shocked but then drawn in, while other times she resists more firmly.
In many Sarah and Jareth fanfictions set in the Lemon Labyrinth, their relationship is often complex. It could be a reimagining of their power dynamic from the original story. Sometimes, it shows a deeper emotional connection that wasn't fully explored in the original work.