Westerners may be more promiscuous but monogamy still rules!

According to a new study which collected data from people in 59 countries, westerners are more promiscuous than those in the developing world.

The new study, the first global analysis of sexual behaviour, says people in western countries have more sexual partners but monogamy is nevertheless dominant across the world.

However multiple partners are more common in rich countries and this is despite developing countries having higher rates of sexually transmitted infections and HIV.

Kaye Wellings, FRCOG, of the London School of Hygiene and Tropical Medicine and colleagues say factors such as poverty and mobility have more of a role in sexually transmitted infections than promiscuity has.

The team also found that teenagers were not having sex earlier, contrary to popular beliefs and there was no universal tread towards earlier sexual intercourse over the past three decades.

Almost everywhere, sexual activity apparently begins for most men and women between 15 and 19 years of age, with men tending to start earlier and most people polled reported only having one sexual partner in the last year.

The first sexual experience was found to be often forced or sold and among girls who marry at a very young age, "very early sexual experience within marriage can be coercive and traumatic."

Those reporting multiple partners were much higher in developed countries, up to a third of under 25s in some areas, whereas only a small percentage in Africa reported the same.

Among the singles, westerners were more sexually active as well.

Two thirds of men and women without a partner in African countries reported they had sex recently, compared to three quarters of those in developed countries which surprised the team as higher rates of STIs were reported in developing countries.

Professor Wellings says this suggests social factors such as poverty, mobility and gender equality may be a stronger factor in sexual ill-health than promiscuity.

The study suggests that unequal treatment of girls and women is a major sexual-health issue, and marriage is no safeguard of sexual health.

It is often more difficult for married women to negotiate safe sex and condom use than it is for single women.

Professor Wellings says the results indicated that flexible approaches to tackling public health were required as men and women have sex for different reasons and in different ways and in different settings.

Wellings says this diversity needs to be respected in a range of approaches geared to whole societies, and to particular groups and individuals within them and should rely on epidemiological evidence rather than myths and moral stances.

The researchers call for providing sexual health services to unmarried young women, supplying condoms, decriminalizing commercial sex and homosexual sex, and prosecuting the perpetrators of sexual violence.

Wellings says to do otherwise will force stigmatized behaviours underground, leaving the most vulnerable people unprotected.

Wellings and colleagues say "Sexuality is an essential part of human nature and its expression needs to be affirmed rather than denied if public-health messages are to be heeded."

The study is published in the Lancet.