In a survey carried out by the social network website gurgle it is suggested that of 2,231 pregnant women polled, 75% experienced a craving, compared to just 30% five decades ago.

Interestingly a third of the cravings were not for food, but items such as coal, soap, toothpaste and sponges.

Of the more usual cravings ice cream, sweets, spicy food, pickled onions, tropical fruit, curry, doughnuts, marmite, peanut butter, potatoes and nuts were popular with chocolate the most craved for.

Unusual cravings included ice, coal, toothpaste, sponges, mud, chalk, soap, matches and rubber, and they affected around 31% of the women.

Odd food combinations were also craved, the most common being pickles and peanut butter, followed by marmite and ice cream - also yearned for were tuna and banana, and fried eggs with mint sauce!

Forty percent found these cravings surfaced in the afternoon or in the evening, with 8% sneaking off for midnight snacks and more than half had partners who are prepared to help deliver the dishes regardless of how odd the food combination was.

Experts suggest part of the reason why cravings appear to be more common might simply be the greater availability of foodstuffs which allows women to satisfy their cravings.

Cravings for non-food items are thought to be related to smell and texture, rather than taste and there is little evidence to support the theory that such cravings help to satisfy a nutritional deficiency.

Experts advise women to be wary of satisfying a craving for a non-food item but say cravings are not usually anything to worry about as long as they are not excessive, and as long as a varied and nutritious diet is generally followed.

Regional health and development agencies could work together to promote seasonal "five a day" choices which would benefit the environment as well as health and the VAT system could be linked directly with healthy eating. Improving production systems would have significant effects on the nutritional quality of foods - quality assurance schemes that take this into account could be beneficial. As food chains become more complex there is a need for more transparency about risks and the sources of ingredients. More support for food production and marketing that also enhances biodiversity, such as salt marsh lamb, and for novel systems such as farming warm water fish indoors, would have benefits for health and for the environment.

Professor Philip Lowe, Director of Relu, said: "Many people today feel out of touch with the land. But the link between rural land and the food we eat is, of course, fundamental to our very existence. There may be ways in which policy can key into that interdependence and benefit both our well being and our environment.

"For example, many people like to eat local food, but we are just beginning to understand the complexity of food miles and to see that local production cannot be the whole answer. Eating foods in season is equally important.

"We strive for a healthy diet, and are told to eat more fish, but how can that be balanced with conserving wild fish stocks? Fish farming hasn't had a good press recently either, but could we do this differently?

"Would changes to the tax system encourage consumption of healthier foods? Or would it be more effective to manipulate the foods people do eat, to make them healthier? And what about food scares and the risks in the food chain? These are all issues that Relu is starting to explore in 'Land to Mouth'."

relu.ac/