Why babies with no teeth need fluoride?

Why babies with no teeth need fluoride?
Fluoride & IQ - The 50 Studies
https://t.co/0KWroMpqTT

Fluoride exposure in utero linked to lower IQ in kids
https://www.cnn.com/2017/09/19/health/fluoride-iq-neurotoxin-study/index.html

There have now been 24 studies from China, Iran, India and Mexico that have reported an association between fluoride exposure and reduced IQ