A pregnant lady uses fluoridated drinking water. All of the following are true regarding exposure of the foetus to fluoride except:
The placenta acts as a regulator and reduces the concentration of fluorides reaching the foetus
The placenta acts as a regulator and increases the concentration of fluorides reaching the foetus
Both
None
There are different views regarding the passage of fluoride across the placenta.
Some authors have said that placenta acts as a complete barrier to fluoride, others have said that it is only partial. 
Some have said that the placenta only acts as a barrier when there is a sudden increase in the maternal plasma fluoride level.

Essentials of preventive and community dentistry 
Soben Peter 
5th edition