NHS figures show 10.5% of women currently smoke at the time of delivery - a drop of only 0.1% on last year.
Over the same period, smoking rates among adults in the UK fell from 17.2% to 15.8%.
The Smoking in Pregnancy Challenge Group said smoking was the cause of too many babies born with health problems.
The group of health charities, which includes the Royal College of Midwives, Action on Smoking and Health and the Lullaby Trust, said good progress had been made in recent years to reduce smoking in pregnant women.
In 2012-13, 12.7% of women in England were smoking when their baby was born, figures from NHS Digital show.
But women living in poorer areas who needed most support to quit smoking were not getting enough help, they added.
Smoking during pregnancy increases the risk of complications such as miscarriage, premature birth, a low birth weight baby and stillbirth.
A Department of Health spokeswoman said it was "encouraging to see smoking rates at their lowest ever levels, but smoking still kills around 79,000 people in England every year so the battle is by no means won".
"We have taken bold action to protect the public by introducing standardised packaging for cigarettes, making it illegal to smoke in a car with a child and covering up tobacco products in shops."
She said a new tobacco control strategy to drive down smoking rates even further would be published "in due course".
Francine Bates, co-chair of the group and chief executive of the Lullaby Trust, said: "We cannot afford to go backwards, having made good progress.
"The government must urgently publish the now long promised Tobacco Control Plan to not only address smoking in pregnancy but ensure that fewer women are smoking when they become pregnant."
The plan for England, which has been in the pipeline since earlier this year, will include measures to narrow the difference in smoking rates between rich and poor.
The charities said good local services were required as well as strong new targets to reach women who needed most help and support.
Hazel Cheeseman, director of policy at Action on Smoking and Health, which co-ordinates the group, said: "This work must continue, and it is important that smoking continues to be a priority if the government's targets to reduce stillbirths are to be met."
Smoking rates during pregnancy are measured differently in the other countries of the UK.
The largest reductions in smoking have been among young people aged 18 to 24, figures from the Office for National Statistics show.
Since 2010, smoking has declined by 6.5% in this group.
About 5.6% of people - 2.9 million - in the UK are now using e-cigarettes.
The reduction in smoking rates among pregnant women in England has slowed down in the past year, prompting concern from health charities.