Hippogriffs: Egg Layers or Livebearers?

I was working on a post, and I was trying to decide if Hippogriffs laid eggs or gave birth to their young live?  Hhhmmm...

I checked my old AD&D Monster Manual, and according to the description of the Hippogriff, and the Griffon, they both lay eggs.  In the RMSS ( Rolemaster Standard System ) Creatures & Monsters no mention of either species being egg layers is made.

However, Griffin/Gryphon females are described as  giving birth to cubs, so that would seem to contraindicate them being egg layers.  Also, Hippogriff offspring are described as foals.  Again with the rear end of a horse that would seem to preclude the laying of eggs?

Now, I know I don't have to follow ANY description of Hippogriff's.  I can decide if they're egg layers, livebearers, or something else.  I've actually reached a decision, and it's kind of fun.  I always like to twist memes inside out, and change them to suit my warped imagination.

Doing my research I also found these terms...

Parturition is the act or process of giving birth to offspring. The terms used to describe parturition vary with the species of animal it is being used to describe. The following are examples of parturition terminology:


A dog whelps and gives birth to puppies
A cow calves and give birth to a calf
A sow farrows and gives birth to piglets
A ewe lambs and give birth to lambs
A horse foals and give birth to a foal

Parturition

So I guess a Hippogriff would foal? What's the term for Griffin's giving birth?