The UK scored just 60 points out of 100 on the index, which is based on a survey of more than 127,000 people worldwide by analytics group Gallup.
That was three points less than the previous year.
The score puts it on par with Kazakhstan, Slovenia, Kosovo and Poland when it comes to providing healthcare for women.
Ireland also scored 60 points.
While the global average was just under 53 out of 100, most Western nations were ranked higher than the UK, which was ranked 30th on the list of 122 countries and territories.
Overall, Taiwan came in first with 70 points and Afghanistan in last place with 22.
The UK government has been accused of “consistently downgrading” women’s health after it was reported in December that waiting times in gynecology in England had tripled in a decade.
On average, women now wait nearly four months for a first hospital appointment with a specialist in gynaecology – yet nearly 38,000 women in England have been on the waiting list for over a year.
The index highlighted problems with the delivery of mental health support in the UK, with the country’s score for women’s emotional health falling eight points in one year to 68 out of 100.
In preventive care such as cancer and diabetes screening, the UK scored just 23 points out of 100.
A separate Hologic survey of 10,000 people in the UK found that ethnic minorities were particularly at risk of losing.
Women in pain in the UK also often have problems accessing a diagnosis. One in five women experienced pain on a daily basis, but more than a quarter were unable to obtain a diagnosis and 15% were only able to do so after eight or more visits to health professionals.
Dr. Nighat Arif, a doctor specializing in women’s health, said she hoped the Government’s Women’s Health Strategy – launched last year – would help improve education and awareness about women’s health.
She said: “Every day in my GP practice I see barriers women face in accessing routine care and even life-saving preventative health measures that can cause unnecessary delays in diagnosis and treatment for women. ”.
A spokesperson for the Department of Health and Social Care said that, along with the Women’s Health Strategy, it also appointed the first Women’s Health Ambassador and took steps to increase the supply and reduce the cost of Hormone Replacement Therapy.
They added: “The strategy sets out our 10-year ambitions to improve the health and well-being of women and girls and to improve how the health and care system listens to all women.”