God does not allow polygamy. It was God's plan from the beginning. God did not intend that when we get we should have many wives. Adam, the first man that God created, He gave him only Eve as wife. Abraham was married to Sarah. It was after Sarah's death that Abraham married Keturah. So, the practice of marrying many wives is not what was planned.
The polygamy came from man’s lustful desires. The people who refuse to be contented with what God has given them are those who always advocate marrying many wives. Polygamy is not a healthy family practice. We should not put that into our consideration.
Families where there is polygamy usually do not have a good family life. We usually hear of contention and division among such families. The children do not enjoy a good life. It doesn't help those children to grow up well. We should not practice polygamy. God did not plan that there should be polygamy.