Fewer pregnant women in Lincolnshire received a flu vaccine last winter, figures suggest.
The Royal College of Obstetricians and Gynaecologists said it was concerned by the record low uptake nationally among pregnant women, and warned that getting flu during pregnancy can be serious.
The NHS recommends that all pregnant women have the flu vaccine, whatever stage of pregnancy they're at, as it will protect both mothers and babies.
Figures from the UK Health Security Agency show that 6,958 pregnant women were registered at GP practices in Lincolnshire over the 2021-22 winter – with 3,224 receiving a flu jab between September and the end of February.
That equated to an uptake rate of 46.3% – down from 48.2% in 2020-21.
Across England, just 37.9% of pregnant women in England got the flu vaccine in 2021-22 – down from 43.6% in 2020-21 and the lowest since comparable records began in 2013-14.
For at risk expectant mothers, uptake was 51.8%, but for healthy pregnant women it was just 36%.
The UKHSA said delays in GP practices updating records following births or loss of pregnancy means the uptake rate is likely to be an underestimate.
And the Royal College of Obstetricians and Gynaecologists said it is possible the true uptake could be higher, but that the figures are "concerning".
Dr Pat O’Brien, consultant obstetrician and vice president of RCOG, said seasonal flu is an unpredictable virus, and strongly recommended all pregnant women get the vaccine.
He added: "Developing flu during pregnancy can be serious for women and their babies because pregnancy weakens the immune system and results in a greater risk of complications and other infections, such as bronchitis than can develop into pneumonia.
“The reduction in uptake might be down to people feeling less concerned about flu last year due to the ongoing Covid-19 pandemic, or may be related to inaccurate information circulating last year about the Covid-19 vaccine and pregnancy."
Uptake rates varied between 55.8% in Stockport, in the North West, and just 18.4% in the London borough of Enfield.
Dr Simon Williams, of Swansea University, said flu vaccine uptake tends to be lower in more economically deprived areas, and also within some black and Asian minority ethnic communities.
The psychology lecturer said these groups have been "historically discriminated against" and marginalised from access to equal healthcare, so might be more hesitant to come forward.
The British Society for Immunology said the Government needs to work with the NHS and local authorities to prioritise important immunisation services and learn lessons from better-performing areas.
Dr Doug Brown, BSI chief executive, added: "For these initiatives to be successful, we must ensure our immunisation services are properly funded and resourced.
"As a matter of urgency, we now need a focus on maternal vaccination to drive forward the work to increase flu vaccine uptake.”