Curvy hips: born-mother

The observation that a woman has 'child-bearing hips' is often dismissed as an old wives' tale.

But voluptuously endowed ladies really are designed by Nature for motherhood, research has revealed.

Those with a narrow waist and big bust - accentuating the hips - are significantly more fertile than others, say scientists.

They are almost three times as likely to become pregnant because of higher levels of certain hormones in their bodies.

And that is apparently the reason why men have been attracted to shapely screen sirens such as Marilyn Monroe and Sophia Loren - and today are beguiled by the likes of Kelly Brook, Jennifer Lopez and Beyonce Knowles.

The preference for large-hipped women has probably evolved over thousands of generations as men subconsciously seek out a partner with whom they are most likely to reproduce, the American study shows. Professor Peter Ellison, of Harvard University in Boston, said: 'In Western societies, the cultural icon of Barbie as a symbol of female beauty seems to have some biological grounding.'

Levels of fertility hormones were 37 per cent higher in women with this 'idealised' shape.

Researchers looked at 119 women and took measurements including bust, waist and hips.

They worked out a waist-to-hip ratio by dividing the waist measurement by the hip measurement.

The average for this figure was 0.72. Narrow-waisted women had an average score of 0.68.

Breast size was defined by comparing the measurement around the breast with a measurement around the abdomen, directly

below the breasts. This reflects how much larger the bust is, relative to the size of the woman's body.

The average figure for this was 1.16. Large-breasted women had an average score of 1.2 on this measure.

Over several months, the scientists collected daily saliva samples from all the women, recording levels of two hormones which are key to fertility - oestradiol, a type of oestrogen, and progesterone.

At a woman's most fertile stage of the month, women who had both a below-average waist to hip ratio and above-average breast size, had levels of the hormone-up to 37 per cent higher than others in the study. Oestradiol levels correlate with the quality o f a woman's eggs, while progesterone is essential to the endometrium - the lining of the womb to which fertilised eggs attach.

Professor Ellison said: 'Physical characteristics, such as breast size and waist-to-hip ratio, function as important features used by human males to assess female attractiveness.

'The 37 per cent relative increase in oestradiol observed in the "narrow waist, large breasts" group could be interpreted as indicating that they would be almost three times as likely to get pregnant as other women.

'Such gains in hormone levels among the preferred mates may lead to a substantial rise in the probability of conception, thus providing a significant " fitness" benefit (in reproductive terms).'

Professor Ellison worked with colleagues from Jagiellonian University in Krakow, Poland, the University of Tromso in Norway and the Ulleval University Hospital in Norway. Their findings are reported today in the Royal Society journal, Proceedings B.