Reproduction, it's a perfectly valid thing that makes total sense. When a mare and stallion love each other very much... Blah... Blah... Blah. Here's a foal. That's how it's supposed to work. Except for when it does not.
Scootaloo and her friends are now in High School and have started to grow up more. Scootaloo has a coltfriend, and everything is fine, until one day she feels sick, and things go from there.
After a freak accident with experimental magic, Rainbow Dash finds herself pregnant with no idea how to handle the situation. With her dreams of joining the Wonderbolts on the line, she begins to panic, like any reasonable pony would do.
When Applejack and Twilight decide to have a foal, Twilight works a little magic to get the job done, though there are unexpected consequences when all of the mane six wake up the next day, all expecting their own little bundle of joy.
An odd quirk of Equestrian law is that the mayor of an Earth Pony town can be challenged to prove her qualifications. Night Flower thinks she's got a shot to beat Mayor Mare.
Cloud Kicker's life has been going just about perfectly. She's got a good job, two beautiful girlfriends, and she's never been on better terms with her friends. Little does she know things are about to get complicated again.
Princess Luna loves her foal very much, although carrying her is a little taxing to say the least. Morning sickness, food cravings, these are just a few of the problems that Equestria's princess experiences as she journeys through her pregnancy.