Perinatal depression can cause preterm labour and low birth weight infants, and may impair the mother’s ability to care for her child. Infants exposed to maternal perinatal depression have higher levels of cortisol and exhibit altered stress responses. This can lead to long-term behavioural and emotional problems which may persist into adulthood.¹

The cause of perinatal depression is poorly understood. Various psychosocial factors have been identified as significant risk factors for the development of perinatal depression. These include stressful life events and chronic daily stress, personal or family history of mental illness, lack of social and family support, poor partner relationships, intimate partner conflict and violence, history of abuse, low socioeconomic status and financial hardship, unplanned or unwanted pregnancy and complications during pregnancy or childbirth.²

A number of biological factors have also been identified as potential contributors to perinatal depression, with the most notable being endocrine changes associated with pregnancy and childbirth. This includes alterations in sex hormones, thyroid hormones and function of the hypothalamic-pituitary-adrenal (HPA) axis. Other factors include alterations in immune function and inflammation, genetic and epigenetic factors, and nutritional deficiencies.³

In truth, the cause of perinatal depression is most likely a combination of both psychosocial and biological factors, with life stressors triggering depression in women with hormonal, genetic and other biological vulnerabilities.4 As natural healthcare practitioners, there is little we can do to alter a woman’s social situation; however we are well placed to support or address the biological factors contributing to perinatal depression, particularly nutritional deficiencies.

Nutritional Factors: Omega 3 DHA

Omega 3 docosahexaenoic acid (DHA) is an essential fatty acid which must be regularly consumed in order to maintain health. As DHA is vital for foetal neurological and retinal development, it is critical to ensure adequate maternal intake during pregnancy. Studies show that foetal utilisation of DHA stores can cause maternal DHA status to decrease by 50% during pregnancy leading to notable deficiency. This may be associated with adverse maternal mental health outcomes, as a growing body of research has linked omega 3 deficiency with major depression.⁵ 

Numerous epidemiological studies have examined the relationship between omega 3 intake, DHA status and perinatal depression. These studies found that low omega 3 intake from seafood and lower DHA levels in the body during and after pregnancy are associated with a significantly increased risk of perinatal depression, while higher intake and higher DHA levels are protective.^5-8 A recent meta-analysis has confirmed that levels of DHA in the body are significantly lower in women with perinatal depression.⁹

Interventional studies using omega 3 fish oil or DHA supplementation have shown mixed results, with some studies finding reduced risk of perinatal depression and others showing no effect. This may be due to differences in study design. Studies using higher doses of 2g combined DHA and EPA earlier in pregnancy were positive, while studies using lower doses or starting later in pregnancy or postnatally showed no effect.10 This highlights the importance of using adequate dosing at the appropriate time.

Nutritional Factors: Vitamin D

Vitamin D functions as an important neuro-modulatory hormone within the brain, and is involved in neurotransmitter regulation, neuro-immune modulation and neuroplasticity. Studies have found that vitamin D deficiency is associated with depression in adults.¹¹ A number of epidemiological studies have been conducted around the world to determine if there is an association between vitamin D status and perinatal depression. A systematic review of these studies involving 11,888 women found that low vitamin D status is significantly associated with perinatal depression, while higher vitamin D levels are protective against the development of perinatal depression.¹² As over 65% of pregnant Australian women are at risk of Vitamin D deficiency, it is vital that vitamin D status is assessed and addressed in all pregnant women.¹³

Interventional studies examining the effects of vitamin D supplementation during pregnancy on the risk of perinatal depression are generally lacking; however one study has demonstrated positive results. Vitamin D supplementation at 2000IU per day for 8 weeks from 28 weeks gestation significantly reduced perinatal depression scores compared to placebo in women with low vitamin D status.¹⁴ 

Nutritional Factors: The Inflammatory Link

Aside from their effects on brain function, a common thread linking the benefits of omega 3 - DHA and vitamin D on perinatal depression may be modulation of inflammation. Studies have found a strong causal link between inflammation and major depression in adults,15 and inflammation is considered one of the biological drivers of perinatal depression.³ Omega 3 deficiency and a high omega 6 to omega 3 ratio are known to contribute to chronic systemic inflammation; correcting this imbalance may account at least partially for the antidepressant effect of omega 3 observed in studies.⁹ Vitamin D is known to have immune modifying effects via modulation of cytokine production and excretion. Vitamin D status in early pregnancy has been found to be associated with inflammatory cytokine levels later in pregnancy. One study has found that vitamin D deficiency is strongly associated with perinatal depression only in the presence of high inflammatory markers.¹⁶

Nutritional Factors: Safety

While further intervention studies are needed to confirm the benefits of omega 3 DHA and vitamin D supplementation in preventing perinatal depression, studies do show supplementation with omega 3 DHA17 and vitamin D¹⁸ are both safe and effective for correcting deficiencies during pregnancy. Additionally, both DHA and vitamin D have secondary benefits for both mothers and their infants. DHA supplementation during pregnancy has been shown to reduce the incidence of premature birth, increase birth weight, improve visual acuity in infants, improve neurological and developmental outcomes and reduce the incidence of developmental delay in infants. Additionally, DHA supplementation during pregnancy reduces neonatal deaths by 33% with no significant adverse effects noted at doses up to 1g of DHA per day.¹⁷ Adequate vitamin D in pregnancy is also important for reducing the risk of pregnancy complications, sustaining foetal growth, foetal skeletal & immune development and respiratory health in the infant,¹⁷ with no adverse effects noted at doses up to 4000IU per day.¹⁸ Therefore it makes sense to reduce the risk of perinatal depression by ensuring adequate intake of these vital nutrients in pregnant women. This can be achieved by prescribing a high quality omega 3 DHA and vitamin D supplement, along with cofactors to support maternal and infant neurological health during pregnancy and in the postnatal period.

 

References

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