If she has a thin waist, a woman is considered very beautiful. All the daughters of Kardama Muni were of the same beautiful feature
SB Canto 3
Lord Brahmā then praised Kardama Muni's nine daughters, saying: All your thin-waisted daughters are certainly very chaste. I am sure they will increase this creation by their own descendants in various ways.
In the beginning of creation, Brahmā was concerned more or less with increasing the population, and when he saw that Kardama Muni had already begotten nine nice daughters, he was hopeful that through the daughters many children would come who would take charge of the creative principle of the material world. He was therefore happy to see them. The word sumadhyamā means "a good daughter of a beautiful woman." If she has a thin waist, a woman is considered very beautiful. All the daughters of Kardama Muni were of the same beautiful feature.