Pouvez-vous donner un peu plus de contexte? 'At first my relation to it is that of a kidney' - ca veut dire quoi? (Je ne sais pas si vous comprenez bien le sens de la phrase parce que sans contexte je ne comprends pas le sens moi-meme.)
My daughter's pure and pearly being requires considerable maintenance. At first my relation to it is that of a kidney. I process its waste. Every three hours I pour milk into her mouth. It goes around a series of tubes and then comes out again. I dispose of it. Every twenty-four hours I immerse her in water and clean her.
C'est une mère qui décrit le début de vie avec sa fille. je vous joins le texte...
I'm going to answer in English - yes, you seem to have gotten the meaning down. I'm not a native French speaker, so I don't know if there are better ways of expressing it - but if you have to translate the rest of the passage as well then this sentence will be explained anyway!