I would think someone on the internet would be able to figure it out... there's plenty of sites dedicated to the subject.
In all seriousness though, there is nothing you can actively do. I think there is an "ugly" trait that slows down how frequently you copulate, other than that, nature just takes it's course through the 'turn' button.
Keep in mind, just because you see a birth announcement, the kid won't be battle ready for a while. When he/she is, they will appear in your capital.