Sporty and bisexual women have more sexual partners compared to their female peers.
The finding emerged from a large-scale study published in the Sexual & Reproductive Health Journal.
The research looked at the sexual habits of 3,000 British men and over 3,800 British women aged 50 and over.
It was also discovered that men in this age range were more likely than their female counterparts to have had more sexual partners.
Around one in five men over 50 have slept with 10 or more partners, compared to one in 12 women of the same age.
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Study co-author Dr Sarah Jackson, of University College London (UCL), said: “Bisexuality in women and homosexuality in men were independently associated with a higher number of lifetime sexual partners.
“And among women, white ethnicity and doing regular moderate to intensive exercise were also associated with a higher number of sexual partners, as was the absence of a longstanding illness.”
Factors such as marital status, income, sexual orientation, race and frequency of smoking, drinking and physical activity were all taken into account.
While, sexual orientation was linked to more lifetime sexual partners in both genders, the factor of income was significant only for men.
“For men, income seemed to be a key influence, with those in the bottom 20% of income and those in the top 20% both reporting higher numbers of lifetime sexual partners.”
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While this study found women over 50 on average have had less sexual partners than their male counterparts, research has also found sex may get better for those in this age range compared to people 30 years younger.
Researchers from the University of Manchester and Manchester Metropolitan University interviewed more than 7,000 over-50s for the report by the International Longevity Centre UK.
They found that a closer emotional bond and growing sexual compatibility are among the reasons why sex gets better as we get older.