This is Bundle Joy (AKA “Bunny” or “Bun Bun”), the mascot for /mlp/‘s pregnancy general. She’s Ponyville’s greatest surrogate mother. Her special talent is that she’s incredibly fertile; if she’s not pregnant (and she’s usually pregnant) she’s always in heat, and a single sperm landing on her vaginal opening will get her pregnant, and she rarely carries less than two foals at once.
She is the first choice for any pony looking for a surrogate, because she never miscarries. She enjoys bringing new life into the world, and is immune to morning sickness. In fact, she’s so used to pregnancy that NOT being pregnant can throw her off her game. In addition, she is also a popular source for ponies who need help with their foals, be it as a babysitter, substitute teacher, wet nurse, or a tertiary midwife. As she’s carrying a foal, she will stay close to the family/stallion the foal is for, and passes the time by baking.
The third image is based on Bun Bun’s cutie mark story:
>Older filly, equivalent of maybe 13, still no cutie mark
>Fooling around with her coltfriend
>They agree on no penetration, to play it safe
>He accidentally lets a drop of pre fall onto her marehood
>A week or so later, she finds out she’s pregnant with triplets