Dairy bosses have dismissed a Harvard study claiming women put their fertility at risk by eating low-fat dairy products.

Scientists at the university's School of Public Health found women who ate two or more helpings of low-fat dairy products on a daily basis were 85% more likely to be unable to ovulate. The study observed 18,000 married nurses over an eight-year period in the 1990s.

However, the FSA said its advice to would-be mums had not changed. "Pregnant women should get a healthy, balanced diet, ideally containing reduced-fat varieties of dairy products," said a spokeswoman.

"We don't think women will eat a higher-fat diet to improve fertility because of this research. These studies come out all the time."

Dr Judith Bryans, head of the Dairy Council, said the science was suspect. "The research methodology used could not take into account all lifestyle and genetic factors that may have contributed to the fertility of the subjects or their partners."