The test diet is based on using olive oil for cooking, an olive oil-based spread and a daily supplement drink enriched with Vitamin D and omega-3 fatty acids for six weeks as an addition to their normal diet.
The effects on fertility will be compared to couples on a control diet of sunflower seed oil for cooking, a sunflower oil-based spread and a sham supplement drink.
The team carrying out the trial at the University of Southampton say the diet could increase pregnancy rates by up to 40 per cent, based on previous research that found increased intake of omega-3 polyunsaturated fats contained in olive oil led to faster embryo development after IVF.