The average age of women undergoing IVF was 35.7 years in 2019, while those needing donor insemination were typically aged 34.5 years.
Both of these figures are older than the average age (30.7) of women having children nationally.
The new HFEA report noted a gradual shift in the number of older women having IVF over the last two decades.
It said that, in 1991, 58% of IVF cycles involved patients under 35, but this fell to 40% in 2019.
The latest data also showed there were 2,435 IVF cycles (4% of the total) involving women in same-sex relationships in 2019 – a four-fold increase compared with 489 cycles in 2009 (1%).
Among women with no partner, there were 1,470 cycles (2%) in 2019, up from 565 in 2009 (1%).
It came as the number of IVF cycles carried out since 1991 in the UK reached more than 1.3 million.
There have also been more than 260,000 donor insemination (DI) cycles and, taken together, the treatments have led to the birth of 390,000 babies.
The HFEA said birth rates for all patients under 43 have got better year-on-year.
In 1991, patients aged 35 to 37 had a live birth rate per embryo transferred of 6%, but this rose to 25% in 2019.
HFEA chairwoman Julia Chain said there have been “many positive changes in the treatment of patients” since the regulator was set up in 1991, “with birth rates increasing, multiple birth rates falling and treatment becoming safer”.
“We know that family structures are changing and continue to evolve, and the fertility sector is providing more options for people to create their families.”
Innovation Minister Lord Bethell said:
“This report highlights the great strides fertility treatment has made over the last 30 years, allowing parents to experience the joy of new life when they otherwise might not have been able to.
“While there has been progress, the sector still faces challenges – there continue to be disparities in people’s experiences of fertility services and more work needs to be done.
“I urge all women, especially those from black or ethnic minority backgrounds, the Midlands and East of England, who have experienced fertility treatment to share their experience with us through our call for evidence so we can create the first Government-led Women’s Health Strategy built on your voices, to improve the health and wellbeing of all women across England.”
The report also found that the level of NHS funding for fertility treatment varied across the UK, with 62% of cycles funded by the NHS in Scotland in 2019, falling to 20% in some parts of England.