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Research suggests vitamin D supplementation reduces depression during pregnancy

Posted on: September 2, 2016   by  Amber Tovey


A recent randomized controlled trial published in the journal BMC Pregnancy and Childbirth discovered that vitamin D supplementation reduced perinatal depression among Iranian pregnant mothers.

Perinatal depression (PD) describes the onset of depression during pregnancy or in the months after childbirth. PD is one of the most common pregnancy complications, affecting approximately one in seven pregnant women.

Prevention and treatment methods for PD play an essential role in a healthy pregnancy as untreated PD can have devastating effects on women, infants and families. PD can interfere with the mother’s ability to connect and care for her baby, which can result in the baby developing sleeping, eating and behavioral problems.

Researchers suggest that the brain requires adequate vitamin D levels for proper development and function. In fact, studies have discovered that the central nervous system contain special receptors for active vitamin D along with enzymes for the activation of vitamin D. This indicates that the brain can locally activate vitamin D, confirming the prominent role that vitamin D plays within the brain. These findings led researchers to evaluate the relationship between vitamin D and psychological symptoms, such as anxiety, depression and cognitive function.

Time after time, research has shown an association exists between vitamin D and these mental health outcomes. However, the majority of these studies have only indicated association rather than causation, meaning whether vitamin D supplementation improves cognition, depression and anxiety remains unknown for the most part. Therefore, researchers from Iran conducted a randomized controlled trial (RCT) to assess the effects of vitamin D supplementation on PD.

The researchers included 169 women who were 18 years or older, without a history of mental illness, without any pregnancy complications and between the gestational age of 26-28 weeks. The women were randomly divided into two groups: the placebo group and the vitamin D group. The vitamin D group received 2000 IU of vitamin D3 daily from 26 to 28 weeks of gestation until childbirth; whereas, the placebo group received a daily dummy pill during this same time frame.

Maternal vitamin D levels were measured at baseline and at childbirth. Researchers used the Edinburgh Postnatal Depression scale to assess depression among the women. Depression scores were evaluated four times: at baseline, 38-40 weeks of gestation, 4 weeks after birth and 8 weeks after birth.

Here is what the researchers found:

  • At baseline, the average vitamin D status was 12.35 ng/ml.
  • At childbirth, the average vitamin D levels were 12.07 ng/ml and 17.46 ng/ml among the placebo group and the vitamin D group, respectively.
  • Although the vitamin D group significantly increased their vitamin D status after taking 2000 IU of vitamin D daily for at least 8 weeks, only 9.7% of the women in the vitamin D group achieved a vitamin D status above 30 ng/ml.
  • Depression scores were similar between the placebo group and vitamin D group at baseline.
  • Average depression scores were significantly lower in the vitamin D group than the placebo group at 38-40 weeks of gestation, 4 weeks after birth and 8 weeks after birth (p < 0.01).

The researchers concluded,

“The present trial showed that consuming 2000 IU vitamin D3 per day in late pregnancy was effective in decreasing depression scores in perinatal period.”

The study provides hopeful findings for all pregnant women. According to this study, it appears that vitamin D offers an affordable, simple and relatively low risk prevention method for PD. Furthermore, the study presents alarming statistics for Iran, illustrating the high prevalence of vitamin D deficiency among pregnant women.

Randomized controlled trials that successfully raise the women’s vitamin D status near 40 ng/ml are needed to fully assess the potential beneficial effects of vitamin D supplementation on PD.


Tovey, A. & Cannell, JJ. Research suggests vitamin D supplementation reduces depression during pregnancy. The Vitamin D Council Blog & Newsletter, 2016.


Vaziri, F. et al. A randomized controlled trial of vitamin D supplementation on perinatal depression: in Iranian pregnant mothers. BMC Pregnancy and Childbirth, 2016.

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