A pregnant lady uses fluoridated drinking water. All of the following are true regarding exposure of the foetus to fluoride except:

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