Learn Finnish: Onko syntyvyys yhä muuttumaton? - Is the birth rate still unchanging?

It is an abstract noun derived from the verb syntyä (to be born). The suffix -vyys (a variation of -uus or -yys) is added to create a word that represents the rate, state, or phenomenon of that action.

What verb form is muuttumaton?

It is the negative participle of the verb muuttua (to change). Adding the suffix -maton or -mätön to a verb's stem creates an adjective meaning 'without doing' or 'un-done'. Here, it translates to 'unchanging' or 'unchanged'.

How would I rewrite this sentence using the current lesson's 'tulla + -maan' future structure to ask 'Will the birth rate be still unchanging?'

You would say Tuleeko syntyvyys olemaan yhä muuttumaton? The auxiliary verb tulla takes the question clitic -ko to become tuleeko, and the main verb olla (to be) goes into the third infinitive illative form, olemaan.

Could I use vielä instead of yhä in this sentence?

Yes, Onko syntyvyys vielä muuttumaton? is also perfectly correct, as both mean 'still'. However, yhä places a slightly stronger emphasis on the continuous, uninterrupted nature of the situation, which sounds very natural when talking about an ongoing statistical trend.