Low vitamin D associated with increased depression risk in pregnancy and after birth

New study highlights the potential link between vitamin D deficiency and maternal mental health, suggesting a need for proactive supplementation.

Study: Is Serum Vitamin D Associated with Depression or Anxiety in Ante- and Postnatal Adult Women? A Systematic Review with Meta-Analysis. Image Credit: Olena Ivanova/Shutterstock.com

Is vitamin D associated with pregnancy and postpartum anxiety and depression? A recent review published in Nutrients sought to explore this question.

The Importance of Vitamin D

Vitamin D is a fat-soluble vitamin synthesized in the body and found in animal, plant products, and fortified foods. Adequate vitamin D levels during pregnancy are essential for both maternal and fetal health, as the high calcium demands of the fetus require elevated maternal serum levels of active vitamin D.

However, recent studies show that 10% of pregnant individuals are severely deficient in vitamin D, while 60% are moderately deficient, with only 1.6% having adequate levels. Vitamin D deficiency, defined as levels below 20 ng/mL (50 nmol/L), and insufficiency, defined as levels between 20-30 ng/mL, are linked to risks of intrauterine growth restriction, low birth weight, miscarriage, and increased likelihood of maternal depression and anxiety.

Vitamin D levels are influenced by various lifestyle and geographical factors, including diet, latitude, season, time spent outdoors, skin coverage, race, body weight, and other health conditions.

Mental Health and Vitamin D

Anxiety and depression are common during pregnancy and the postpartum period, with risk factors including alcohol use, smoking, previous mental health conditions, marital or social stress, negative thinking patterns, financial stress, lower education levels, and ethnicity.

Theories around pregnancy-related depression involve hormonal imbalances, inflammation, and changes in the hypothalamic-pituitary-adrenal (HPA) axis. Vitamin D is known to have anti-inflammatory and antioxidant properties and is involved in synthesizing neurotransmitters like serotonin, dopamine, and noradrenaline. Vitamin D receptors are also present in regions of the brain responsible for mood regulation.

Thus, vitamin D is believed to play a significant role in neuropsychological processes that affect mood and mental health. Previous studies examining vitamin D’s relationship with pregnancy-related depression are dated, with methods varying widely. “The evidence currently available in the literature is insufficient to establish a role for 25(OH)D supplementation in the prevention or treatment of ante- and postnatal depression.”

The current review incorporates recent studies from 2020 onward to update findings on this association and identify methodological limitations that could guide future research.

About the Study

The researchers included studies that measured vitamin D concentrations in adult pregnant and postpartum women, using validated tools to assess the presence of anxiety and/or depression. The review included 15 cohort studies, nine cross-sectional studies, and one case-control study, each assessed for bias risk using a validated checklist.

Of these, seven cohort studies, three cross-sectional studies, and one case-control study had a moderate risk of bias, while five cohort studies and six cross-sectional studies were considered low-risk. All studies used reliable screening tools for depression and anxiety. Additionally, 21 of the 25 studies accounted for potential confounding factors such as sociodemographic and economic background, health conditions, supplement use, lifestyle, and pregnancy well-being.

Of the 25 studies, 12 focused on antepartum depression, while 17 examined postpartum depression. Three studies investigated antepartum anxiety, and two looked at postpartum anxiety.

Vitamin D in Pregnancy and Depression

The study found depression and anxiety occurred in 7%-49% of pregnant women and 12.4%-37.8% of postpartum women, while vitamin D deficiency or insufficiency was present in 15.7%-82.6% of participants.

Seven studies found an association between low vitamin D levels and depression during pregnancy, and nine found similar associations postpartum. Among the antepartum studies, three were cohort studies and four were cross-sectional. For postpartum depression, five cohort studies and three cross-sectional studies supported this link. Additionally, the case-control study reported more severe postpartum depression symptoms with lower vitamin D levels.

On average, vitamin D levels were significantly lower (by approximately 4.6 ng/mL) in women with antepartum depression. This trend was particularly notable in studies using the Centre for Epidemiological Studies Depression scale, which showed a mean difference of -7.66 ng/mL between those with and without depression, though this difference was not observed with the Edinburgh Postnatal Depression scale.

Similarly, postpartum depression was associated with a smaller decline in vitamin D levels (about -2.4 ng/mL), according to the Beck Depression Inventory Scale, though the Edinburgh Postnatal Depression Scale did not reveal a significant difference. After adjusting for other variables, postpartum depression risk was found to be twice as high in individuals with vitamin D deficiency.

One cross-sectional study showed significantly lower vitamin D levels in pregnant and postpartum women with anxiety, but this result was not observed in two cohort studies.

Conclusions

The review found an inverse association between vitamin D levels during pregnancy and the postpartum period and the likelihood of depressive symptoms. However, the evidence linking serum vitamin D concentrations to anxiety symptoms in the antepartum period remains inconclusive.

“Solid evidence of the association between serum 25[OH]D concentrations allows for the formulation of practices and actions aimed at preventing maternal and fetal complications.” Public health initiatives that promote vitamin D supplementation during pregnancy and postpartum, as well as programs to increase awareness of vitamin D’s role, could help improve maternal physical and mental health while reducing healthcare costs.

While the findings align with prior studies, the conclusions are limited by potential biases, variable study methods, and small sample sizes. Longitudinal studies that follow pregnant and postpartum women over extended periods are essential to better understand the strength of these associations.