Trans fats 'raise infertility risk'

Eating more unhealthy trans fats could make it harder for women to get pregnant, according to new US research.

Scientists found that for every 2 per cent increase in the amount of calories a woman got from trans fats instead of carbohydrates, her risk of infertility increased by 73 per cent.

If the trans fats replaced healthier omega-6 polyunsaturated fats, the figure rose by 79 per cent.

The team at the Harvard School of Public Health in Boston studied data from 18,555 healthy women who were trying to get pregnant between 1991 and 1999.

A total of 438 were diagnosed with ovulation-related infertility.

For every 2 per cent of calories women got from trans fats instead of monounsaturated fats, the risk of infertility more than doubled.

The team estimated that if a woman is eating 1,800 calories a day, 2 per cent of energy intake in trans fats would equal just 4 grams.

Trans fats are made from a liquid vegetable oil base which is put through a chemical process called hydrogenation to make it more solid and extend shelf life.

Research has linked them to increased cholesterol levels and a greater risk of coronary heart disease.

Several fast food chains are moving to eliminate trans fats in their products, and New York is introducing a ban on the fats in all its 25,000 restaurants.