Tinishya Marshall, who gave birth when she was just 13, was last seen a week ago, pushing her daughter Sophie in her pram near her home in Bristol.
Concerned relatives think the youngster may be with her boyfriend, 16-year-old Howard Norman, who is believed to be Sophie's father. He is also missing.
Tinishya's mother Liz, pleased with her daughter to contact her, telling reporters: 'I'm desperate to hear from her.'
Mrs Marshall revealed that Tinishya had not taken any baby clothes with her, and had given no indication that she was planning on leaving.
'The last I saw of her was on Friday and she seemed perfectly normal and didn't mention anything about going away.'
Tinishya, who left school to have her baby, was described by her mother as a 'quiet girl' whose pregnancy had come as a shock to the whole family. She had been dating Howard Norman for around a year before she became pregnant, and continued to see him after the birth, even though her family had banned her from doing so.
Mrs Marshall said her daughter had taken motherhood 'in her stride': 'It's tough because of her age but she's done really well. She's never really struggled.'
Friends of the teenagers claimed they had planned to go to Devon together. An Avon and Somerset Police spokesperson said there was 'growing concern' about the welfare of the baby as none of her belongings or change of clothes were taken.