The figures - 18 cases confirmed by blood tests so far this year as opposed to seven reported cases throughout 1992 - have been described by a child health charity as 'only the tip of the iceberg'.
The disease can cause heart, hearing and eyesight problems in children whose mothers have been infected in the first few weeks of pregnancy. If the virus is present after 16 weeks then it is very unlikely to damage the foetus, according to Pat Tookey, research officer for the National Congenital Rubella Surveillance Programme.
'We have to wait for the babies to be born to see the rise in congenital rubella syndrome. We will not be able to see this until the end of the year or the beginning of next year,' she said.
Today, the National Council for Child Health says that not enough has been done to warn would-be mothers and pregnant women of the dangers of the outbreak of rubella.
'We feel that when this trend started to appear, there should have been official warning issued to doctors to encourage them to increase testing and immunisation of vulnerable women,' said Fiona Fountain, director of the council.
Women should check their immunisation status with their doctors before becoming pregnant, she said. 'These cases are probably only the tip of the iceberg. Many women ignore what could be rubella. It is perfectly possible to ignore because the symptoms can be so mild. The only way to be sure you are immune is to have a blood test.'
Rubella immunisation was introduced in Britain in 1970, originally targeting schoolgirls and susceptible adult women. Now, the council said, some girls are not being protected because GPs are taking over immunisation from health districts.
A survey by the council this year showed that target rates for in-school immunisation are being achieved in only 39.4 per cent of district health authorities. Almost half are falling below the 90 per cent uptake rate set by the Department of Health.