The number of midwives in Kent and Medway has failed to increase, despite concerns about a national shortage of maternity staff.
According to a report from the Royal College of Midwives (RCM), 875 were working across the county in May, compared to 879 last year.
The union estimates NHS England gains just one extra midwife for every 30 trained - predominantly due to the high number of professionals leaving the service.
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The report also suggests Brexit could be having an impact on the number of maternity staff.
During the last financial year, just 33 midwives who trained elsewhere in the European Union registered to work in the UK - compared to 272 two years previously, before the referendum.
During the same period, the number of European midwives leaving the register jumped from 160 to 234.
Gill Walton added: "We have around 1,700 EU-trained midwives registered to work in the UK, and they will be caring for tens of thousands of women every year.
"My fear is that if Brexit goes ahead, especially without a deal, then their numbers could quite simply collapse.
"More needs to be done to guarantee their right to stay and work in the UK post-Brexit."
The role of a midwife has also become more demanding in recent years, as the profile of women using maternity services continues to change.
Last year, 55% of births were to women in their thirties or older, the highest since records began in 1938.
The government has committed to training an extra 3,000, and officials that, combined with a fall in the number of births, this will be enough to tackle the problem.