Men have twice as many sexual partners as women over the course of their lives, research suggests。

The Health Survey for England found that men reported having 9.3 different partners on average, with a quarter of men boasting of more than 10 conquests。

However a third of those questioned admitted they were only estimating the number of notches on their bedposts。

By contrast, women had a mean average of 4.7 sexual partners in their lives so far, with a quarter having just one. They were more likely to be certain of the number of lovers they had had。

Among older women, monogamy was even more common with 40 percent of those aged between 55 and 69 saying they had only ever had one sexual partner。

Older women were also far less likely to be sexually active, with 36 percent saying they had not had a partner in the past year. Overall a fifth of respondents aged between 16 and 69 had been chaste。

The poll of 14,000 people, published by the NHS Information Centre on Thursday, suggested that younger generations were losing their virginity at ever earlier ages and taking more risks。

Its chief executive Tim Straughan said the annual report, which asked questions about sex for the first time, "paints a picture of sexual behaviour which is changing over the generations with younger women tending to begin having sex younger"。

A fifth of men and one in seven women said they had had sex before their sixteenth birthday, and the median age for first sex was 17. Overall fewer than one in 10 of those questioned were still virgins。

But among 16 to 24 year-old women the proportion who had lost their virginity before 16 – which would mean their partners were breaking the law – rose to 27 percent。

In addition, 15 percent of young women had had between two and four different sexual partners in the past year。

The Public Health Minister, Anne Milton, said: “Young people should think carefully before having sex - it's not something to rush into. Consider seriously if it's right for you, what contraception to use and the best way to protect yourself from sexually transmitted infections。”

调查显示，英国男性一生中性伴侣的数量是女性的两倍。

英格兰健康调查发现，男性平均一生有9.3个性伴侣，四分之一的男性还有10个以上的性伴侣。

不过，三分之一的被调查者承认他们只能说出性伴侣的大概数目。

相比之下，女性平均一生有4.7个性伴侣，四分之一的女性只有一个性伴侣。她们对性伴侣的数量一般更确定。

在年龄较大的女性当中，一夫一妻制更普遍，55到69岁的女性有40%称自己只有过一个性伴侣。

年龄较大的女性性活跃的可能性也低得多，36%的年长女性说自己在过去一年中一个性伴侣也没有。总体上，16到69岁的受访女性有五分之一一直保持贞洁。

英国国家医疗服务体系信息中心周四发布的这一调查涵盖了1.4万人，调查结果显示年轻一代失贞时的年纪更小，而且冒的风险更大。

信息中心的执行总监蒂姆?斯特劳汉说，这一年度报告“描绘出几代人性行为的变化，更年轻的女性通常更早发生初次性行为”。该调查首次询问和性相关的问题。

五分之一的男性和七分之一的女性说他们在16岁生日前就有过性行为，而发生初次性行为的平均年龄为17岁。总体来看，不到十分之一的受访者仍保持处子之身。

16到24岁的女性当中，在16岁前就失贞的比例升到了27%，这意味着她们的性伴侣也不到英国进行合法性行为的最低年龄线。

此外，15%的年轻女性在过去一年中有二到四个不同的性伴侣。

英国公共卫生部部长安妮?米尔顿说：“年轻人应该在发生性行为之前先仔细地考虑一下——性行为并不是那种可以贸然进行的事情。认真地想想这么做是否适合自己，应采用什么样的避孕手段，以及用何种最佳方式来保护自己不传染上性传播疾病。”