Here is some academic references:
Bearer of a fair offspring, name by which Demeter was invoked in the Thesmophoria, Ar.Th.299, Alciphr.2.4, cf.IG14.205 (Acrae); or her nurse, Ar. ap. Phot.; epith. of the Moon, Hymn.Mag.5.31; of the Earth, Apollod. ap. Phot.:—neut. pl., Καλλιγένεια θύειν offer sacrifice to Demeter K., Alciphr.3.39 (nisi leg. τῇ Κ.).
An early mention of the pool of Mnemosyne can be found in the Petelia Gold Tablet, an Orphic inscription from between 300-200 BC:
You will find in the halls of Hades a spring on the left,
and standing by it, a glowing white cypress tree;
Do not approach this spring at all.
You will find another, from the lake of Memory
refreshing water flowing ...
KALLIGENEIA (Calligeneia) was the nymph nursemaid of the goddess Demeter and her daughter Persephone. She was worshipped as a goddess of the Eleusinian Mysteries.
Kalligeneia was perhaps the Naiad-nymph of the sacred Kallikhoros (Callichorus) spring of Eleusis. Alternatively her name might simply be a title of the earth-goddess Gaia.
It’s not a goddess, but instead a day.
The quote is from Kalligeneia: Fertility and Feminine Focus on an
Athenian Bell Krater, an undergraduate research paper by Suzanne Allison and offers a nice description of Kalligeneia:
The final day of the festival is the Kalligeneia, “beautiful birth”, when the women would feast and celebrate. The portrayal of ...