Sure Start maternity grant cuts begin
About 150,000 families will miss out on maternity grants each year due to a cut which is being imposed from 24 January.
The £500 per child Sure Start maternity grant is being restricted to the first child in a family.
It comes before a series of other benefit cuts that will be imposed from April, which will affect housing benefit and tax credits.
Up until now, the £500 had been available to parents for each subsequent child as well.
The decision to restrict the grants was criticised by the charity, Family Action, which has condemned it as part of "an assault on family finances".
Family Action's chief executive, Helen Dent, told the BBC: "We know from speaking to the parents who use our family support and perinatal services just how vital this money is - helping to provide the essential items which come with a new baby."
Sure start maternity grants are designed to assist with the burdensome costs of having a baby, such as the pushchair, cot, clothes and other equipment.
Applicants need to be on one of a number of benefits, including income support or income-based jobseeker's allowance.
Those on the higher rates of child tax credit, and some working tax credit claimants, can apply as well.
The restriction to one child applies from 11 April 2011, but a grant can be claimed from 11 weeks before the week in which a baby is due.
So the legislation is being brought into force on 24 January 2011.
However, if the baby is due before 11 April, parents can still apply for the grant, even if they have other children.
The government was keen to impose the new rule from January because any delay would have cost the exchequer £1.4m a week in grants.
The cut will save £73m a year.
The Department for Work and Pensions (DWP) has described the practice of giving the grant to successive children in a family as "outdated, expensive and unfair".
Steve Webb, a minister at the DWP, said: "Restricting payment in this way ensures that the limited resources available support families when they need it most."
"Expenditure is inevitably highest when a new baby is the only child in the household and there are no baby items that can be reused or recycled," he added.
There is a concession for parents whose other children are 16 or over.
If they have a new baby, they can still apply for the grant.
The cut in maternity grants was announced in the June 2010 Budget as part of the coalition's deficit reduction plans.
The new restriction comes on top of the abolition of Child Trust Funds, the planned axing of the health in pregnancy grant and changes to child tax credits.
"It is just one measure in a package of cuts to financial support for new parents and their children," complained Helen Dent from Family Action.