The act in which a character lays multiple eggs at the same time from a single orifice, rather than the typical one-by-one .

Notes:

• Eggs must come from a single orifice (i.e. pussy, nipple, etc.). Having each breast birthing one egg, for example, does not count as unison birth.
• Often involves interspecies pregnancy or hyper belly
• Falls under the multiple_oviposits tag, but allows for a more specific search of this type of multiple birth.

If the character is live-birthing rather than laying eggs, use the unison_birth tag instead.