Work and pensions secretary Iain Duncan Smith has four children. As a wealthy man, perhaps it is fortunate that he has no need to rely on child benefit to feed them.

IDS wants to see child benefit capped at two children per family, believing that there is a booming industry of 'baby farming', where families are deliberately having children in order to milk riches from the public purse.

At present, all parents with young children are given benefit worth £20.30 a week for the first child and £13.40 for each subsequent child.

Lurid headlines about workshy families living in luxury paint a picture that few social workers who engage with them would recognise. In June, Eric Pickles trumpeted a £450m crackdown on a group of 'problem' or 'troubled' households said to cost the taxpayer £9bn. Social workers reacted strongly at the time to the notion of 'trouble-shooters' being sent in to households to 'eyeball' families. The report that this policy was based on, authored by 'Troubled Families Tsar' Louise Casey has subsequently faced claims of unethical inaccuracy by lecturer Nick Bailey, and pressure from the Full Fact organisation has led to both The Sun and The Daily Mail having to run corrections on the story.

Think about how much food you could put in a shopping basket for £13.40. That's before you even think about buying clothes or anything else that a child might need. Even if a family had ten children, that would still only be just over £100 per week extra, which doesn't go very far when you have multiple mouths to feed.

The reality is that child poverty is on the rise in the UK. The Child Poverty Action Group is currently predicting that child poverty will rise to 4.2 million by 2020. The Eye of the Storm report, published jointly by the Children's Society, Action for Children and the NSPCC,warned in July that the number of children living in vulnerable families in Britain is likely to rise to over one million by 2015. Six out of ten of these poor children are living with a working parent, another statistic that the government chooses not to publicise when it aims its sight on 'troubled' families.

BASW has previously warned about the dangers of bringing back Victorian notions of the deserving and undeserving poor, and this is yet another example, spreading the myth that people deliberately have children in order to fund an alternative lifestyle.

Bridget Robb, acting chief executive of the British Association of Social Workers, is keen to point out that far from the workshy stereotype; many families are forced to claim benefits because of the impact of the recession.

"Political rhetoric is frequently targeting the poorest and most vulnerable. The traditional working class, without work, are increasingly being described by politicians almost as if they have no place in our society", she says.

"Where is the government's evidence base for claiming that people are deliberately having children in order to claim more benefits? Conservatives may be seeing their stance as a potential vote winner, but it simply is not a picture that we recognise. Our members are seeing more and more children and families sliding into poverty, and all more cuts will do is put more strain on public services that are already at breaking point."

Ms Robb also feels that by relying on rhetoric rather than evidence, the government is potentially placing children at risk, as there are numerous different types of families in society, and many people are likely to find themselves in family units with multiple children that they hadn't planned for.

"When people forge new relationships, both partners will often have children already, where will a cap on child benefit leave such families? Kinship carers, where a relative in a child's wider family choose to foster them, are also likely to lose out. The more children you have, the more they cost, so it is not as if the household income increases in real terms. This is yet another attack on low income families, and it will be the children who will bear the brunt of it. All this policy will do is punish children for being born," she concludes.

Social workers report that the recession is putting families under increasing pressure. The number of children being referred for care proceedings has reached record levels, and the NSPCC has seen an 80% surge in calls on neglect in the last 18 months. Food bank charity the Trussell Trust recently said that it has fed almost 110,000 people since April, compared with a total of 128,697 people during the whole of the financial year of 2011/12. We know from our members that demand for social care services is increasing. In our recent survey, 54% of the 1,100 UK social workers questioned said their caseloads were "unmanageable".

These are the statistics that should most concern the government, but it does not suit their political aims. Just as its 'troubled families' initiative lumped together outdated and inaccurate statistics about people who have ticked boxes such as having previously claimed disability benefit or having had mental health problems, and equated them to a 120,000 person strong threat to society, so too we now have these claims about families with more than two children being on the make.

When IDS talks of people 'cutting their cloth' according to their circumstances, he forgets that many people will have planned their families before the recession, when they could afford them, and will be no longer able to afford them without state assistance when they have lost their jobs through no fault of their own. What are such families supposed to do with these 'extra' children now?

Iain Duncan Smith has four children. He is lucky that he comes from a privileged background that equipped him to live a privileged adult life in turn. Not everyone is so fortunate, and who decides how many children are enough?

The government should instead focus on easily accessible family planning services, supported by good GPs and health care staff, and on helping poor children to escape poverty, rather than demonising large families.

We don't currently live in a country that practices population control, and the poor children that the government seeks to punish simply for existing are already here and a part of our society. We can't send them back, nor should we wish them away.

Follow Hayley Meachin on Twitter: www.twitter.com/@BASW_UK