Women who eat low-fat yoghurt while pregnant increase their chances of having children who develop asthma and hay fever, a study has found.
Daily yoghurt consumption raised the odds of giving birth to a child who suffered from asthma by the age of seven 1.6 times.
Eating yoghurt almost doubled a mother's chances of her child being diagnosed with hayfever.
However, the same study of almost 62,000 women in the Netherlands found that drinking milk during pregnancy had a small protective effect.
The researchers wanted to see whether fatty acids found in dairy products could help prevent childhood allergies.
They are still investigating the surprising link.
One possibility is that yoghurt consumption acts as a proxy marker for other dietary and lifestyle factors.
It may also be that non-fat nutrient components in yoghurt play a part in increasing allergy risk.
Researcher Dr Ekaterina Maslova, from the Harvard School of Public Health in Boston, US, said: "We will further investigate whether this is linked to certain nutrients or whether people who ate yoghurt regularly had similar lifestyle and dietary patterns which could explain the increased risk of asthma."