Iris remains alive in the Flash comics. The creators have kept her as an important and ongoing presence, and her role continues to evolve and contribute to the overall narrative.
Barry Allen became The Flash after being struck by lightning while working in his lab. The lightning was charged with chemicals, which altered his body's chemistry and gave him super - speed. This event transformed him into the Scarlet Speedster we know as The Flash.
Yes, there are likely fanfictions out there with such a plot. 'The Flash' has a large and creative fanfiction community, and the idea of Barry and Caitlin having a pregnancy could be an interesting exploration of their relationship in the fan - created stories.
One of the best is 'The Flash: Rebirth'. It delved deep into Barry Allen's return and his complex relationship with the Speed Force. It also reintroduced many elements of his character and his place in the DC Universe.