The reason for cravings is unclear
Pregnancy cravings are much more common among modern women than previous generations, a survey suggests.
Three-quarters of those surveyed experienced a craving, compared to just 30% five decades ago.
It found a third of cravings were not for food, but items such as coal, soap, toothpaste and sponges. Ice and chocolate were also popular.
The poll of 2,231 pregnant women was carried out by the social network website gurgle.com.
Laundry soap: 5%
Percentages of women reporting unusual cravings, around 31% of total
Chocolate was the most common food craving, followed by ice cream, sweets, spicy food, pickled onions, tropical fruit, curry, doughnuts, marmite, peanut butter, potatoes and nuts.
Mothers-to-be reported cravings for odd combinations of food, the most common being pickles and peanut butter, followed by marmite and ice cream.
Other combinations mentioned included tuna and banana, and fried eggs with mint sauce.
Women reported that cravings mostly struck in the afternoon (40%) or in the evening (38%), with only 8% sneaking off for midnight snacks.
Fiona Ford, of the University of Sheffield's Centre for Pregnancy Nutrition, said part of the reason why cravings appeared to be more common might simply be that greater availability of foodstuffs made it easier for women to act on their desires.
She said cravings for non-food items - a condition known as pica - were probably often related to smell and texture, rather than taste.
There was little evidence to support the theory that such cravings helped to satisfy a nutritional deficiency, she added, as the body was unlikely to be able to absorb nutrients from items such as coal or mud.
Ms Ford said: "Ice is a good of satisfying a craving for texture, and a non-toxic way, rather than chewing plaster off the walls, or chewing match heads, or some of the other things we have had.
"The advice is that is if it is for a non-food item then women should be quite careful and discuss it with their midwife.
"If it is just for something that has a very strong taste as long as it does not stop you eating a general, varied, healthy diet it does not matter."
Dr Joanne Lunn, a nutrition scientist at the British Nutrition Foundation, said the reasons for pregnancy cravings were not clear.
She said: "It is common to find foods that you normally enjoy taste different, or that you don't feel like eating them at all.
"You might also find yourself craving foods that you would usually never touch.
"These cravings are not usually anything to worry about as long as they are not excessive, and you manage to eat a varied and nutritious diet overall."