Hourglass figure fertility link

Jayne Mansfield was famed for her hourglass figure

Men have long held up women such as Jayne Mansfield as icons of female attractiveness.

But researchers now say this isn't just a superficial judgement - women with hourglass figures are more likely to become pregnant.

Writing in a Royal Society journal, they say this is because women with large breasts and narrow waists have higher hormone levels.

They say this offers a biological reason for Western views of beauty.

The study, in the journal Proceedings B, looked at 119 Polish women.

Their weight and body fat was checked, and researchers also measured the circumference of their waist, hips, breast and under their breast.

They were categorised as large breasts/narrow waist, large breasts/broad waists, small breasts/narrow waist or small breasts/broad waist.

Researchers also took morning saliva samples from the women throughout one menstrual cycle which were measured for levels of two hormones; 17-b oestradial (E2) and progesterone.

High levels of these hormones are good indicators that a woman will successfully become pregnant.

'Good nutrition'

It was found that women with higher breast to under-breast ratios (large breasts) or low waist to hip ratio (WHR) had higher hormone levels.

In Western societies, the cultural icon of Barbie as a symbol of female beauty seems to have some biological grounding Dr Grazyna Jasienska, Harvard University

Women with both had 26% higher levels of E2 on average, and 37% higher E2 levels mid-cycle than women with in the other three categories.

Women with low WHR also had higher progesterone levels.

Writing in Proceedings B, the researchers led by Dr Grazyna Jasienska of Harvard University, said the hourglass figure was popular in Western cultures, but not in others across the world.

She said men in non-Western societies did not seem to favour women with hourglass figures, and broader figures, indicating good nutritional status, were considered most attractive.

"However, in Western societies, the cultural icon of Barbie as a symbol of female beauty seems to have some biological grounding," added Dr Jasienska.

Dr Martin Tovee of the University of Newcastle, who has carried out research into what makes people attractive to others, told BBC News Online the Royal Society paper was not conclusive.

"What the results of this paper suggest is that the ratio of bust-to-waist may predict hormone levels.

"This is in turn may predict fertility, and this might be a reason why the bust-waist ratio might predict attractiveness."

He added other studies of female attractiveness showed that when images of real women are examined, whether their figure is in proportion was considered the most important feature.

Height, bust size and waist-to-hip ratio were considered less important, he said.