Melbourne, March 28 : Japanese researchers have linked the soft bones in a baby's skull to a deficiency of vitamin D, by finding that women who are pregnant over the summer season are more likely to have healthier babies.
Researchers at the Kyoto University Hospital in Kyoto, Japan, have shown that babies with softer skulls are more likely to be in the womb over winter, as their mothers don't get enough vitamin D, which is absorbed from sunlight.
They also found that breast-feeding without vitamin D supplementation could prolong the condition, called Craniotabes, which might lead to a risk of serious health problems later in life, including decreased bone density and type 1 diabetes.
Dr Tohru Yorifuji from the Kyoto University Hospital said his team's study of more than 1100 newborns in Japanese hospitals revealed that pregnancies over winter could lead to problems in babies.
"Craniotabes, the softening of skull bones, in otherwise normal newborns has largely been regarded as a physiological condition without the need for treatment," News.com.au quoted Dr Yorifuji, as saying.
"Our findings, however, show that this untreated condition may be the result of a potentially dangerous vitamin D deficiency," he added.
The researchers found craniotabes present in 22 percent of 1,120 infants studied about a week after birth. Babies born at sunnier times of the year were less likely to have the condition, suggesting it is linked to sun exposure during pregnancy.
At one month of age, blood tests found that about 7 percent of the babies had evidence of low vitamin D levels. But when researchers analyzed the method of feeding, they found that 60 percent of breast-fed babies had low levels of the storage form of vitamin D compared to none of the babies who received a vitamin D-supplemented formula.
"The incidence was highest in (babies) born in April-May and lowest in those born in November," the researchers said.
"Otherwise, the incidence of craniotabes was not significantly related with the maternal age, number of pregnancies, birth weight, or weeks of pregnancies," they added.
Dr Yorifuji said mothers should also be concerned about how much vitamin D their baby needed while feeding.
"Until more research is done on the effects of perinatal vitamin D deficiency, we suggest treating breast-fed infants with craniotabes with vitamin D, or preferably, treating all pregnant women with vitamin D," he said.
A lack of vitamin D in adults has previously been linked to increased risks of multiple sclerosis, type 1 diabetes and other diseases.
The findings are to be published in the May edition of the Journal of Clinical Endocrinology and Metabolism.