The 22-year-old woman from Kessel-Lo (Flemish Brabant) went missing a while ago.
Her body was found buried in woodland. The police have not yet been willing to comment on how she died.
The suspects who have been detained include the 19-year-old father of the woman's baby and a friend.
It is understood that the suspect's family objected to any relationship with the dead woman because a marriage had already been arranged with another woman.