Is it obligatory to fulfill a vow to name a newborn a specific name, if the wife made this vow unintentionally or unknowingly before pregnancy?

Vowing to name a newborn a specific name is a permissible vow. A vow concerning a permissible act does not necessitate fulfillment. Therefore, it is not obligatory to name the newborn with the name the wife vowed. You may name him according to what has been agreed upon. It is more cautious to offer expiation for an oath.