Thursday, 22 February, 2024
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Vitamin D deficiency linked to premature births

Women with the lowest levels of vitamin D were about 1.5 times as likely to deliver early compared to those with the highest levels, a US study has found. Medicinenet reports that the finding held true even after the researchers accounted for other factors linked to preterm birth, such as overweight and obesity and smoking.

"Mothers who were deficient in vitamin D in early parts of pregnancy were more likely to deliver early, preterm, than women who did not have vitamin D deficiency," said Lisa Bodnar, associate professor of epidemiology and obstetrics and gynaecology at the University of Pittsburgh, who led the study.
Although this study found a strong association between vitamin D levels and preterm birth, Bodnar noted that the study wasn't designed to prove that low vitamin D levels actually caused the early deliveries. "We can absolutely not prove cause and effect," she said.

The US Centres for Disease Control and Prevention provided funding for this research.
For the new study, researchers looked at just over 2,100 women who didn't give birth early, and more than 1,100 who delivered preterm. All of the women included in the research had given birth to single infants between 1999 and 2010.

The researchers found that as the women's blood levels of vitamin D decreased, the chance of preterm birth increased.

There is no universally agreed upon definition of deficient vitamin D levels, according to Bodnar. In general, according to the NIH, levels below 30 nmol/L (nanomoles per litre) are too low for good health, while levels of 50 nmol/L are probably sufficient for most people.

In the study, Bodnar and her colleagues grouped women as less than 50 nmol/L, 50 to 74.9 nmol/L, and 75 nmol/L or above. Before adjusting for other preterm birth risks, the researchers found that more than 11 percent of the mothers in the lowest vitamin D level group delivered before 37 weeks. About 9% of mothers in the middle group delivered early and 7% of those in the highest level group did, the findings showed.

When the researchers adjusted the data to account for other pre-term birth risk factors, they saw a similar association between lower vitamin D levels and preterm birth, according to the study.

So, how might vitamin D offer some protection against pre-term birth? Possibly by helping to reduce bacterial infection in the placenta, which can trigger an early delivery, according to Bodnar.

But, she cautioned, "women should not run out and start taking vitamin D supplements. They should take a pre-natal vitamin (which includes D) as recommended by their doctor."

[link url="http://www.medicinenet.com/script/main/art.asp?articlekey=186219"]Full Medicinenet report[/link]
[link url="http://journals.lww.com/greenjournal/pages/results.aspx?txtkeywords=Lisa+Bodnar"]Obstetrics & Gynaecology abstract[/link]

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