The woman, believed to be Zehra Duman from Melbourne, is being held at a refugee camp in north-east Syria and says she wants to come home because her baby is sick.
However, Mr Morrison has pushed back against pleas for help.
The prime minister declared he would not put any Australians at risk by helping home-grown extremists wanting to come home from the Middle East.
“They have made their decisions and if they are Australian citizens, well there’s a process for us to deal with them under Australian law, and they will face the full force of Australian law, should they be in a position to seek to come back to Australia,” he told 3AW radio.
Mr Morrison said it was a “great tragedy” Islamic State sympathisers had dragged their children into war zones.
“They have placed their children in this horrendous position,” he told reporters in Melbourne on Thursday.
“They have to take responsibility for those decisions to join up with terrorists who are fighting Australia.
“The children are innocent victims in the terrorist acts of their parents.”
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