Vitamin D link to depression in mothers

Research by The Kids Research Institute Australia shows a link between low vitamin D during pregnancy and post-natal depression.

The research findings were recently published online in the Archives of Women's Mental Health journal.

Lead author and psychologist Dr Monique Robinson said that with an increasing number of studies linking low vitamin D with mental health outcomes, the team wanted to know what effect low vitamin D in pregnancy may have on later postnatal depression symptoms in mothers.

"This is important because pregnancy may be a time where vitamin D levels are low, due to covering up more and getting out less, and also dietary changes such as limiting fish intake and liver products due to mercury and listeria concerns," Dr Robinson said.

"Using data from the Western Australian Pregnancy Cohort (Raine) Study, we took a measurement of vitamin D at 18 weeks gestation from 796 Caucasian mothers and then measured postnatal depressive symptoms at 3 days after giving birth.  

"We adjusted for season of birth as levels naturally are different in different seasons."

Dr Robinson said the study found that those mothers who were in the lowest quartile of vitamin D levels, corresponding to vitamin D deficiency, had more symptoms of depression postnatally compared with those in the highest quartile.

"These women were nearly 3 times as likely to report a high score for postnatal depression than those with the highest vitamin D levels," Dr Robinson said.

"The next step is to look at vitamin D throughout the entire pregnancy and the effect on postnatal depression instead of just the one time point."

Dr Robinson said the team wasn't sure of the exact Vitamin D mechanism involved in the link. It is possible that vitamin D levels are merely a surrogate of a healthy lifestyle and outdoor activity in the sun.  

"Other research studies have shown links between Vitamin D and mental health outcomes but more research in this area is needed," she said.  "Postnatal depression is also complex in terms of causes but this might be one risk factor that we can learn more about given it is easy to modify."

Dr Robinson cautioned that women should consider safe sun exposure guidelines when looking at ways to increase their Vitamin D levels.

Vitamin D can be found naturally in foods such as salmon, liver and eggs and in supplement tablets but the major source is sun exposure.  

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About the Raine Study
The Raine Study is jointly conducted by The Kids for Child Health Research and the University of Western Australia. The study started in 1989, when 2900 pregnant women were recruited into a research study at King Edward Memorial Hospital to examine ultrasound imaging. The mothers were assessed during pregnancy and health and lifestyle information was collected on the mother and the father. After the children were born, they were assessed at birth, at one year, then two, three and five years of age. Further follow-ups of the cohort have been conducted at eight, ten, 14, 17, 20 and now 23 years of age. Find out more at www.rainestudy.org.au