Softening of the skull bones in normal-looking babies might reflect vitamin D deficiency during pregnancy, according to a new study accepted for publication in the Journal of Clinical Endocrinology & Metabolism (JCEM). Furthermore, breast-feeding without vitamin D supplementation could prolong the deficiency, which might lead to a risk of serious health problems later in life, including type 1 diabetes and decreased bone density.

“Craniotabes, the softening of skull bones, in otherwise normal newborns has largely been regarded as a physiological condition without the need for treatment,” said Dr. Tohru Yorifuji, of Kyoto University Hospital in Japan. “Our findings, however, show that this untreated condition may be the result of a potentially dangerous vitamin D deficiency.”

For this study researchers evaluated 1,120 newborns for incidence of craniotabes, and at 5-7 days of age, 246 neonates (22 percent) were found to have craniotabes. Researchers also found the incidence of craniotabes had obvious seasonal variations. This clear seasonal variation strongly suggests that the condition is associated with prenatal vitamin D deficiency and likely reflects the amount of sun exposure of pregnant women.

Most importantly, vitamin D deficiency in neonates, could persist into later life, especially in breast-fed infants who do not receive a formula containing vitamin D supplementation. In this study, more than half of the breast-fed infants with craniotabes showed statistically significant low levels of serum 25-OH vitamin D, the storage form of vitamin D. Some of those infants also had symptoms of an overactive parathyroid gland consistent with vitamin D deficiency.

Vitamin D deficiency has not received as much attention as it once did, however several recent studies have reported a resurgence of the condition, even in developed countries. Vitamin D deficiency classically presents with skeletal manifestations such as rickets in childhood or the softening of bones in adults. In addition, vitamin D deficiency in adults can also lead to increased incidence of immunological diseases such as multiple sclerosis, type 1 diabetes, or even colorectal cancer.

“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,” said Yorifuji (Newswise).

A rapid release version of this paper will appear in the May 2008 issue of JCEM, a publication of The Endocrine Society, and is available online here:

Vitamin D deficiency in pregnancy linked to soft skull bones in babies