More than a quarter of mothers in Blackpool are smoking while pregnant, new NHS figures have revealed.
In the research from 2014/15, 27.2% of women were smoking at the time of birth, in contrast to only 2.1% of women in central London, the Health and Social Care Information Centre (HSCIC) said.
The North fared badly with Durham, Darlington and Tees Area Team recording the highest prevalence, with one in five women (19.9%) reporting that they were smokers at the time of giving birth. In contrast, the lowest percentage of smokers - after London - were the south of England, the Midlands and east of England.
However, overall the figures of pregnant women smoking are the lowest since records began in 2006/7, with 11.4% of pregnant women on average smoking when they gave birth.
Professor Kevin Fenton, director of health and wellbeing at Public Health England (PHE), said: "We are very encouraged that the rate of smoking during pregnancy continues to fall and that we're on course to reach our 11% ambition.
"However, further action is required to support those who find it more difficult to stop."
Statistics were taken in England form 1 April 2014 to 31 March 2015.
In 2013/14, the average number of pregnant women smoking was higher at 12%, and in 2006/7 it was at 15.1%.
A year earlier the figure was 12%, continuing the steady decline since 2006/7, which saw a high of 15.1%.
According to the NHS, the harmful effects of smoking while pregnant include abnormal foetal growth and raising the risk of a baby being stillborn.
On the website, it states: "Every cigarette you smoke contains over 4,000 chemicals, so smoking when you are pregnant harms your unborn baby.
"Cigarettes can restrict the essential oxygen supply to your baby, so their heart has to beat harder every time you smoke."
Louise Silverton, director for midwifery at the Royal College of Midwives, told the Mail Online: "Targets for reduction are fine but they need to be backed up with resources.
"What is needed is retention of local authority funding for family based smoking cessation to include pregnant women."
Silverton said health providers should ensure there are enough midwives with the time to offer women support, advice and referral to smoking cessation services.
Previously, a study by Professor Eileen Mclaughlin showed that smoking during pregnancy harmed children's later fertility.
Professor McLaughlin, co-director of the Priority Research Centre in Chemical Biology at the University of Newcastle in New South Wales, Australia, said on HuffPost UK Parents: "It would be unethical to deliberately expose pregnant mothers and their offspring to the toxins in cigarettes – we already know that smoking in pregnancy harms the baby in the womb – as babies are often born small and vulnerable to disease.
"So, we did a study using a mouse animal model, which directly mimics human smoking, to look at what effects the mothers smoking during pregnancy and breast feeding has on the fertility of their male pups.
"Our results showed that male pups of 'smoking' mothers have fewer sperm, which swim poorly, are abnormally shaped and fail to bind to eggs during in vitro fertilisation studies.
"This is the first time we have been able to prove conclusively that male baby exposure to cigarette toxins in pregnancy and early life will damage later life fertility."