A survey by Jo's Cervical Cancer Trust revealed the NHS is facing new challenges to attendance amid the pandemic, as some women avoid making appointments over fear of catching Covid-19 or putting extra strain on the health service.
Women aged 25 to 49 are invited for screening every three years, while those aged 50 to 64 receive invitations every five years.
NHS Digital data shows 75% of the 146,071 women in Buckinghamshire eligible for a smear test by the end of 2019 had been screened – the point at which the latest data is available.
Although that was up from 74% over the same period in 2018, it meant 37,097 women in the area were missing out on the potentially life-saving programme shortly before the Covid-19 crisis struck.
Cervical screening requires a test that looks for changes in the cells of the cervix which could develop into cancer.
A small sample of cells is taken from the cervix using a soft brush.
Across England, 72% of eligible women had been screened by the end of December, up slightly from 71% the year before.
Cervical screening services across England are slowly unpausing following disruption during lockdown, which saw invites suspended and appointments delayed.
Jo's Cervical Cancer Trust said while low uptake was "already a concern" before Covid-19, the pandemic has created further barriers to attendance.
A survey of 851 women carried out by the trust reveals delayed and cancelled cervical screening appointments have left nearly four in 10 women feeling worried, while 12% say they are less likely to attend than before the pandemic. Some 13% think it is best to put off getting a smear test at the moment.
A quarter of women said they are worried about their risk of catching the coronavirus if they attend a screening, while fears around safety (11%), not wanting to put "additional strain" on the NHS (15%) and uncertainty over changes to services were also selected as reasons for concern.
Robert Music, the trust's chief executive, said: “Cervical screening isn’t always the easiest test and we must try to prevent the coronavirus making it even harder.
"We want every woman to have the information and support they need to feel able to make decisions about their health.
"While it can be difficult if you are unable to get an appointment at the moment, providers of cervical screening services and the government are weighing up the risk of a delayed appointment against the risk of coronavirus. The aim is to keep you, and health workers, as protected as possible.”
Dr Nikki Kanani, GP and director of primary care for the NHS in England, said plans are in place to start offering screening appointments as soon as possible, and measures will "soon be in place" to protect patients from the coronavirus.
She said: “While cervical cancer takes a long time to develop, we would strongly encourage any patients who are worried to seek help from their GP if they have symptoms, and if you are invited to attend a screening appointment, please do."