This is a minimal structure I've come up that might work for you: content of `templates.preg.maternal-changes`:

---
id: 0l1omgwyc3g4327nrv0ljju
title: Maternal Changes
desc: 'The physical changes manifested in the body of the mother in order to compansate for the increase demands duriing the pregnancy'
classification:
  - '[[RG.551-591]]'
  - '[[RG.940-991]]'
updated: 1654664260893
created: 1654663967751
---

content of `preg.schema.yml`:

version: 1
imports: []
schemas:
  - id: preg
    children:
      - maternal-changes
    title: preg
    parent: root
  - id: maternal-changes
    template: templates.preg.maternal-changes
    namespace: true

With this schema and tree structure, whenever you add a note under

preg.maternal-changes.*

, the template will be applied to that note.