'Baby concentration camps!' exclaimed the man standing next to me as we listened to Gordon Brown announce that, from now on, all 16 and 17 year old parents who are on benefits will be placed in "a network of supervised homes".

Indeed. In Labour's attempt to take the Conservative's "broken society" claims on, the prime minister was announcing a radical policy to deal with "the children having children", as he described them.

"It cannot be right, for a girl of sixteen, to get pregnant, be given the keys to a council flat and be left on her own," Brown said.

He's right of course - a young mum who lacks the support of partner, family or friends will struggle and deserves some support.

But, on the face of it (and the Department for Children, Schools and Families is "waiting for some further details from officials"), this seems to be a very blunt object to deal with a very sensitive issue.

What if you are a sixteen-year-old who has the support of family, perhaps even a partner, but just happens to be poor and on benefits? And with rising unemployment there will be more and more of them. Do you also get sent to the supervised home? Even if you have no record with the police, or previous contact with social services and, most importantly, are legally allowed to have sex and have children.

There are very good examples of where this kind of intense support for young mums can bear results - see the Guardian's recent coverage of the Books and Babies project in south Wales - but I can think of two problems with the announcement by Brown.

First, this introduces an element of compulsion. In existing schemes, the young mums have agreed to use a service and, we can safely presume, are ready to take something from it and use it positively. A care home filled with teenagers who have been forced to be there will be very different - the atmosphere will be far more adversarial. Perhaps there will also be a prison effect - one not so bad egg is incarcerated with a bunch of much worse eggs and learns a whole bunch of bad habits.

Secondly, the care service budget is already overstretched and this new scheme, instead of providing all-singing support and care for young mums, is more likely to be as damaging as institutional care can be - both for the young mums and the babies they have just had.

Having watched a friend have to live in a mother and baby unit for two months because social services incorrectly believed that she may have harmed her new born baby, I can safely say that, if these supervised care homes, resemble that mother and baby unit, they will do more harm than good.

This was a small, semi-detached house used to house four young, teenage mothers and their babies. Visits were limited to two hours a day for each resident because of space and had to be conducted in a bare conservatory, or the garden on a sunny day. My friend was watched in her room by CCTV, questioned about how she cared for her (second) baby to the point that she began to doubt her abilities as a mother, was bullied by one of the other young mums and watched other residents she had bonded with have their babies taken into care, something that also threatened her.

Luckily, she had had the support of her parents, her partner, her partner's parents, the courts threw out the case, and she was able to go home, to be reunited with her three-year-old daughter.

Imagine now, a similar scenario for a teenage mum who doesn't have so much support.

Let's hope this is just a case of political posturing, making Labour look tough, and that the detailed policy is not nearly as hardline as Brown has painted it.