Perhaps the plot could revolve around the cultural differences between Vulcan and human parenting. Spock's family might have certain expectations for the baby's upbringing, while Uhura's family has their own ideas. They would then need to find a middle ground. Also, the baby could be a target for some villains who want to use the baby's unique genetic makeup for their own evil purposes.
Perhaps in the fanfiction, an experiment gone wrong results in a baby that is part Spock and part Uhura in a very unexpected way. They have to come to terms with this new situation and protect the baby from those who might want to use it for unethical research. The story could also explore how their relationship changes as they face this unique parenting situation.
Perhaps the baby is born during a time of intergalactic unrest. Spock and Uhura are then forced to protect their child while also fulfilling their duties in Starfleet. The baby could be a symbol of hope and unity between the two species, and they have to ensure its safety from those who might see it as a threat. They might also have to deal with jealousy or suspicion from some of their colleagues who don't understand their relationship.
Another aspect could be the cultural implications. The Vulcan culture is very different from human culture. So, the fanfiction could delve into how they teach their baby about both cultures. Will the baby be more inclined towards the Vulcan way of life with its strict self - control, or will the human side's love for creativity and spontaneity prevail?
Their relationship could deepen as they share the experience of raising a child together. They'll have to rely on each other more, and through the process, they might discover new aspects of their love for one another. For example, seeing Spock be gentle and nurturing with the baby could make Uhura fall in love with him all over again in a different way. And Uhura's warmth and care for the baby might make Spock feel more connected to his human side.
With the baby's arrival, they would have less time for just the two of them. But this could bring them closer in a different way. Spock might become more in touch with his emotions because of the baby, and Uhura would be more understanding of Spock's Vulcan side as they navigate parenting. For example, when the baby has a fever, Spock uses his Vulcan knowledge to try and cool the baby down, and Uhura is impressed by his calmness and resourcefulness.
Another idea is that Spock and Uhura are sent on a secret mission together. During this mission, they are stranded on an unknown planet. They have to rely on each other to survive, and in the process, they face challenges that test their relationship. For example, they might encounter a hostile species that forces them to work together in new ways.
One plot idea could be that female Naruto discovers she's pregnant during a time of peace in the Hidden Leaf Village. She might struggle at first with the idea of being a mother while still having her ninja duties. She could then start to train in new ways that are less dangerous so she can protect her unborn child. Her friends, like Sakura, would be there to support her through the pregnancy, giving her medical advice and just being there for emotional support.
One possible plot idea could be that Hancock discovers she is pregnant with Luffy's baby. This could cause a stir in Amazon Lily as they deal with the idea of their empress having a child with an outsider. Meanwhile, Luffy might be oblivious at first, still on his adventures, until the news reaches him and he has to figure out how to be a father while still pursuing his dreams of becoming Pirate King.
In the fanfiction, Uhura could be the main caregiver for the baby at first. As Spock observes her with the baby, he starts to feel a new kind of emotion towards both of them. He begins to participate more in the baby's care, like teaching it Vulcan meditation techniques. This way, their relationship grows gradually. Also, the baby could have a special connection with Spock due to his telepathic abilities, which further cements their relationship.
One great Spock Uhura fanfiction is 'Love in the Stars'. It beautifully portrays their relationship with a lot of emotional depth. The author does a wonderful job of showing how their different personalities complement each other.