Newcastle-based research has found that women with higher vitamin D levels during pregnancy had children who were less likely to wheeze.
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Such children were also less likely to need medical intervention for wheezing, a common asthma symptom.
Dr Megan Jensen, of Hunter Medical Research Institute, said children born to women with asthma were "already at an increased risk of poor respiratory outcomes in early life".
Dr Jensen, of the University of Newcastle, said these children also face increased risk of developing asthma.
"If that's something we can change with nutrition, which is generally quite feasible and acceptable for mothers during pregnancy, that would be fantastic," she said.
The researchers are now examining what stage of pregnancy is most important for vitamin D intake related to infant respiratory health.
"That will help us design a trial where we'll look at improving vitamin D levels through supplements, for example, in women with asthma while pregnant," she said.
Vitamin D has been gaining a lot of attention lately, particularly in relation to COVID-19.
An Italian study released last week, found a high prevalence of vitamin D deficiency was found in COVID-19 patients with acute respiratory failure.
"Patients with severe vitamin D deficiency had a significantly higher mortality risk," the University of Bari study said.
"Severe vitamin D deficiency may be a marker of poor prognosis in these patients, suggesting that adjunctive treatment [like supplements] might improve disease outcomes."
Dr Jensen, of the University of Newcastle, said there was evidence that vitamin D boosts the immune system and helps ward off viral infections, like the common cold, which are a common trigger for asthma.
A University of Minnesota study, released last month, found that low vitamin D levels "have been associated with an increase in inflammatory cytokines", a hallmark of COVID-19 and its so-called "cytokine storm".
They were also linked to "a significantly increased risk of pneumonia and viral upper respiratory tract infections".
Adrian Martineau, a professor of respiratory infection and immunity at Queen Mary University of London, recently told The Guardian that: "Vitamin D could almost be thought of as a designer drug for helping the body to handle viral respiratory infections".
"It boosts the ability of cells to kill and resist viruses and simultaneously dampens down harmful inflammation, which is one of the big problems with COVID."
Nevertheless, the National Institute of Health Care Excellence in the UK found "there is no evidence to support taking vitamin D supplements to specifically prevent or treat COVID-19".
"Vitamin D is important for bone and muscle health. It has also been hypothesised that vitamin D may have a role in the body's immune response to respiratory viruses," it said.
A Curtin University study released last year said there was a "high prevalence of vitamin D deficiency worldwide".
"Despite living in a relatively sunny country, nearly one in four Australian adults are vitamin D deficient," it said.
A National Health and Medical Research Council report in 2017 said there was "increasing recognition that a significant number of Australians and New Zealanders may have less than optimal [vitamin D] status".
Vitamin D is essential for human health and is often called a hormone, rather than a nutrient.
"We get most of it from exposure to the sun. Food sources of vitamin D include oily fish like salmon, egg yolks and fortified foods," Dr Jensen said.
"Of course, in Australia we have to be careful of sun exposure because of melanoma."
Despite our abundant sunshine, vitamin D deficiency in Australia isn't surprising to Dr Jensen, particularly for those who work indoors and cover their skin.
"We shouldn't start ignoring sunscreen or hats. But I think there's an element of safe sun exposure to get vitamin D in our body," she said.
Research has also suggested lower levels of vitamin D are linked to mood disorders and depression, but further research is needed in this area.
Labels for vitamin D supplements tend to focus on their use for bone and muscle health. And studies suggest they can boost energy levels and mood.
Some vitamin D supplements state that they also maintain "healthy immune system function".
Dr Jensen said the focus on the vitamin's role in bone health was due to a well-established scientific consensus.
She was involved in an individual patient data meta-analysis [which combines multiple scientific studies] that showed vitamin D "reduced risk of acute respiratory infections".
"And it reduced the number of severe asthma exacerbations that needed treatment with systemic corticosteroids."
This study, released last year, found that Vitamin D supplementation was safe and protected against acute respiratory infections.
