One of the issues that bring us back to the changes arising from the New Orthographic Reform is, without a doubt, the use or not of the hyphen, given that some changes operated precisely in this aspect. Thus, as we have to adjust to them as soon as possible, we chose the prefix “pre” for our conversation, given that sometimes it is written with a hyphen, sometimes without.
In this sense, it is suggestive to go back to some concepts related to the accentuation rules, especially when it comes to stressed and unstressed monosyllables. To do so, we invite you to access the text “Accentuation”.
Well, it is worth noting that the use or not of the hyphen is intrinsically linked to such assumption (tonicity). So, let us pay attention to the clarifications below:
# When the prefix “pre” is demarcated as tonic, that is, when it has phonetic autonomy, the use of the hyphen is necessary. Just remembering that because of this aspect the graphic accent is evident. So let's look at some cases:
PRE-TEENAGE
PRE-CONTRACT
PREDATED
PRE-ELECTORAL
PREFABRICATED
PREHISTORY
PRENATAL
PREPAID...
# In cases where the prefix “pre” appears as unstressed, that is, without phonetic autonomy – reason why it needs to be supported by the following syllable ─, it is not followed by the use of a hyphen and, obviously, it does not receive a graphic accent. Let us verify the following cases:
PREHEAT
PREHEAT
PRE-ANUNCIATION
PRECONCEIVED
PRECONDITIONED
PREDETERMINED
DEFAULT
FORESEEN...
Source: Brazil School - https://brasilescola.uol.com.br/gramatica/prefixo-pre-uso-ou-nao-hifen.htm