Babies and children are less likely to develop croup if their mothers take fish oil and vitamin D supplements during pregnancy, according to a new study.
Croup is a viral chest infection that affects young children and causes a characteristic 'barking' cough, a hoarse voice and difficulty breathing.
Croup is common and usually mild, but some children will need hospital treatment and breathing support.
Protecting against croup
There is currently no vaccine against the pathogen that causes this disease.
But this study, the first of its kind, suggests that both vitamin D and fish oil could have an influence on the immune system.
The findings will be presented at the European Respiratory Society International Congress in Barcelona, Spain.
The supplements
The study, presented by Dr Nicklas Brustad, included 736 pregnant women divided them into four groups.
They took different doses - high or standard - of vitamin D supplements, and either fish or olive oil daily from their 24th week of pregnancy until one week after they gave birth.
Researchers monitored the children until they were three years old and any who were suspected of suffering from croup were diagnosed by a doctor or via their medical records.
There was a total of 97 cases of croup amongst the children.
The results
Overall, children whose mothers took the fish oil had an 11% risk of croup, compared to 17% in the children whose mothers took olive oil (a 38% decrease).
Children whose mothers took high-dose vitamin D had an 11% risk of croup, compared to an 18% risk in those whose mothers took the standard-dose vitamin D (a 40% decrease).
Dr Brustad said: "Our findings suggest that vitamin D and fish oil could be beneficial against childhood croup in sufficiently high doses. These are relatively cheap supplements meaning that this could be a very cost-effective approach to improving young children's health.
"We are not sure of the exact mechanisms behind the beneficial effects of vitamin D and fish oil, but it could be that they can stimulate the immune system to help babies and young children clear infections more effectively."
Pregnancy supplements
The research team have already investigated other potential benefits of vitamin D and fish oil during pregnancy, including its effects on bone development, the central nervous system, body composition and asthma.
They will continue to follow the children in the study and plan to investigate why some children are more prone to infections in childhood than others.