Smear test rates have fallen in Brighton and Hove and remain the worst in the south east.
And health chiefs suspect that many who miss out on their tests are too embarrassed about their bodies.
The rate in Brighton and Hove fell to 68.6 per cent in 2016-17 from 69.5 per cent the year before.
NHS England said: “Brighton and Hove has the lowest take up rates for cervical screening in the south east as across the country screening rates fall to a 20-year low.
“Every day nine women in the UK are diagnosed with cervical cancer and three women will lose their lives to the disease.
“Cervical cancer is the most common cancer in women under 35 but is largely preventable thanks to cervical screening and the HPV (human papilloma virus) vaccination programme.
“But statistics show that the number of women aged 25 to 29 years of age being screened for cervical cancer is the lowest in any age group and numbers attending for screening are falling year on year.
“This year the first girls who were vaccinated against HPV are also eligible for screening as they reach their 25th birthday.
“Surveys undertaken by cancer charities indicate embarrassment and a lack of understanding of the causes of cervical cancer may be behind the fall in numbers attending.
“The number of women dying from cervical cancer has halved over the past 28 years as a result of the NHS screening programme as well as improvement in treatment.
“Despite this success over 5,000 women are diagnosed with cervical cancer each year.
“Some of these women may have delayed coming forward for screening for a variety of reasons but treatment of early changes detected by screening can prevent women from developing cancer.”
Max Kammerling, consultant in public health medicine and head of the public health screening and immunisation team for Surrey and Sussex, said: “It is really important for young women to understand the importance of attending cervical screening as it can detect pre-cancer abnormalities, which, if left untreated, may develop into cancer.
“Screening is for people without symptoms as a preventative measure.
“The screening test is relatively simple, takes about five minutes and is performed by the practice nurse at your GP surgery.
“Ninety five per cent of results will be normal and of those that are not, the vast majority can be treated very easily and will never develop in to cancer.”
NHS England and Public Health England are supporting Cervical Cancer Prevention Week which runs from Monday 22 January to Sunday 28 January.
The week aims to raise awareness of the importance of cervical screening and its role in preventing cancer, as well as encouraging women to go for their screening test when invited.
NHS England’s screening and immunisation teams also work with GP practices to increase awareness.
Dr Kammerling added: “We have noticed a fall in attendance of younger women over the past few years and are concerned that this trend may increase due to misunderstanding of the level of protection that the HPV vaccination offers.
“Although they are protected against the two most common HPV types that cause 70 per cent of cervical cancers, the risk is not completely eliminated and screening is still an important part of preventing cancer.”
Robert Music, chief executive Jo’s Cervical Cancer Trust, said: “Cervical cancer is largely preventable with cervical screening (smear tests) providing the best protection against the disease.
“Screening prevents up to 75 per cent of cervical cancers yet the number of women attending is at a 20-year low in England with over one in four women in Brighton and Hove missing their test in the last year.
“There are many reasons women don’t attend ranging from simply putting it off to worrying it will be embarrassing or painful to not knowing what the test is and why it’s important.
“During Cervical Cancer Prevention Week we want to encourage women to talk to their friends, mothers and daughters about the steps they can take to reduce their risk of cervical cancer.”
At the Montefiore Hospital, in Hove, consultant gynaecologist James English said: “The single biggest risk factor for developing cervical cancer is not being regularly screened.
”It is a preventable disease. The signs that it may develop can be often be spotted early and it can be treated before it even fully starts.
“While around 750 women each year die from cervical cancer in the UK, it appears that nearly 1.5 million women a year are missing out on their tests.”
The Montefiore Hospital said: “Women aged 25 to 49 are invited to attend cervical screening, or smear tests, every three years. Those aged 50 to 64 are invited every five years.
”The screening can detect abnormal (pre-cancerous) cells in the cervix in order to prevent cervical cancer.”
Mr English said: “It is important to get the message across that cervical screening is not a test for cancer but instead allows for detection of abnormalities at an early stage.
“The routine of attending a cervical screening should be an important part of every woman’s health regime but for many women this message just isn’t getting through.
”Early detection is key to increasing survival rates so educating everyone about the disease, its symptoms and ways to prevent it is very important.”