More women than men are working as doctors at Southern Health, new figures show.
A think tank has urged trusts to provide flexible working arrangements and reconsider their promotion processes to help women reach top positions.
The medical profession has historically been dominated by men, but the gender balance has become more even in recent years.
Figures from NHS England show 58% of the 225 doctors working at Southern Health NHS Foundation Trust were female, with figures taken in September.
In 2018, there were 100 female and 90 male doctors working for the trust.
Women make up around three-quarters of all NHS staff, including the bulk of nursing and support roles. At Southern Health, 86% of the 1,845 nurses working for the trust were women.
Meanwhile just 90 of the 22,000 midwives across England were men, while 46% of doctors were women, up from 44% in 2018.
These figures are rounded to the nearest five.
Research from the King's Fund think tank found the pay gap between male and female doctors fell from 20.9% in 2018 to 5.5% last year.
Danielle Jefferies, a policy analyst at the organisation, cautioned the NHS should not "sit on its laurels".
With ongoing issues around staff retention, Ms Jefferies said the NHS "cannot afford" to lose women to jobs outside the health service. A greater number of female doctors could also improve care for women and help deal with health inequalities, she added.
She urged trusts to introduce better flexible working policies, and make sure their process for promotions is "fair and equitable" – across ethnicity and disability as well as gender.
According to government pay gap data, male staff have higher hourly salaries at most NHS trusts – including at Southern Health, where men earned 2.3% more than their female colleagues as of March 2023.
Men occupied 23% of the highest-paying positions at the trust, despite making up 18% of all employees.
Saffron Cordery, deputy chief executive at NHS Providers said it was "deeply concerning" the pay gap has persisted.
She said: "NHS trust leaders are committed to promoting equality and ensuring fair and equal opportunities for staff regardless of protected characteristics.
"Addressing the underrepresentation of women in certain roles, particularly in higher-paying positions, remains a priority.
"But beyond headline figures, trusts need to be supported nationally to tackle the root causes of discrimination in the workforce."
She added a recent plan from NHS England would help close the pay gap and ensure flexible working and menopause policies.
An NHS England spokesperson said: "The NHS is clear that trusts must continue to do all they can to reduce their gender pay gap, which is why we have instructed organisations to analyse their data on pay and put in place an improvement plan by the end of 2024, and this should be monitored and tracked by their board.
"NHS trusts have also been asked to implement an effective flexible working policy including advertising flexible working options on organisations’ recruitment campaigns."