DHA and Brain Development in Pregnancy: What Expecting Mothers Need to Know

Author: Rohan Smith | Functional Medicine Practitioner | Adelaide, SA

Quick Answer

Docosahexaenoic acid (DHA) is a long-chain omega-3 fatty acid that plays a structural role in the developing brain and nervous system. During pregnancy—particularly in the third trimester—DHA is actively transferred from mother to fetus and incorporated into neuronal cell membranes, supporting brain growth, visual development, and neural signalling (1–3). Inadequate maternal DHA intake has been associated with less optimal neurodevelopmental outcomes, making dietary intake during pregnancy clinically important (4–6).

What Is DHA?

DHA (docosahexaenoic acid) is a polyunsaturated omega-3 fatty acid that is highly concentrated in the brain, retina, and central nervous system. It forms a key component of neuronal cell membranes, where it influences membrane fluidity, synaptic function, and communication between nerve cells (1,2).

Unlike some other fatty acids, DHA cannot be synthesised efficiently in sufficient quantities from precursor fats. As a result, adequate levels depend largely on dietary intake, particularly from marine-based sources (3).

The Role of DHA in Fetal Brain Development

Maternal–Fetal Transfer

During pregnancy, DHA is preferentially transported across the placenta from mother to fetus. This transfer increases substantially during the third trimester, a critical period characterised by rapid fetal brain growth and cortical development (4,5).

Neuronal Structure and Function

DHA contributes to several foundational processes in neurodevelopment, including:

• Neuronal membrane integrity and flexibility
• Synapse formation (synaptogenesis)
• Myelination and efficiency of neural signalling

Together, these processes underpin learning capacity, memory formation, and visual processing later in life (6–8).

DHA and Cognitive Outcomes

Research examining prenatal DHA exposure suggests associations with aspects of early cognitive development, including attention, visual acuity, and problem-solving ability. Outcomes vary depending on factors such as dosage, timing of exposure, and baseline maternal DHA status (9–11).

Lower maternal DHA levels during pregnancy have been linked to less favourable neurodevelopmental markers, highlighting the importance of adequate intake during gestation rather than relying on postnatal intake alone (12).

DHA and Maternal Emotional Well-Being

DHA also plays a role in neurotransmitter function and neuroinflammatory regulation. Lower omega-3 and DHA status has been associated with an increased risk of mood disturbances, including depressive symptoms during and after pregnancy, although these relationships are complex and influenced by multiple factors (13–15).

This association is biologically plausible given DHA’s involvement in neuronal signalling pathways and inflammatory balance within the brain, which are increasingly recognised as important factors in mental health regulation (14).

How to Support Adequate DHA Intake

Dietary Sources

Fatty fish such as salmon, sardines, trout, and mackerel are rich sources of preformed DHA. Many clinical and public health guidelines suggest consuming low-mercury fish two to three times per week during pregnancy to support omega-3 intake (16).

Supplementation

For individuals who avoid fish or have increased nutritional requirements, DHA supplements—particularly those derived from algal oil—offer a direct source of DHA without mercury exposure. Supplementation may be appropriate when dietary intake is insufficient (17,18).

Fortified Foods

Some eggs and dairy products are fortified with DHA and can make a modest contribution to overall intake. However, these foods are unlikely to meet DHA requirements on their own (19).

When DHA Intake May Require Closer Attention

• Low or absent fish and seafood consumption
• Vegetarian or vegan dietary patterns
• Multiple or closely spaced pregnancies
• Conditions that impair fat digestion or absorption, including certain gut health disorders linked to the gut microbiome

In these contexts, individualised nutritional assessment may be appropriate (20).

Key Takeaways

• DHA is a long-chain omega-3 fatty acid that plays a structural role in fetal brain and nervous system development.

• Maternal DHA is actively transferred to the fetus, particularly during the third trimester when brain growth accelerates.

• Adequate DHA intake during pregnancy is associated with more favourable neurodevelopmental markers, including attention and visual development.

• Low maternal DHA intake has been linked to less optimal neurodevelopmental outcomes in some studies.

• DHA also contributes to maternal neurological and emotional health through its role in neurotransmission and inflammatory regulation.

• Dietary intake from low-mercury fish is the primary source of DHA, with supplementation considered when intake is insufficient.

Personalised Pregnancy Nutrition Support

Pregnancy places unique demands on nutrients involved in brain development, including DHA. At Elemental Health and Nutrition, we provide evidence-informed, personalised nutrition support to help clarify individual needs during pregnancy.

If you’re planning a pregnancy or currently expecting, booking an appointment can help ensure key nutrients are adequately supported for both maternal health and fetal development.

References

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6. Martinez M. Tissue levels of polyunsaturated fatty acids during early human development. J Pediatr.
7. Crawford MA et al. The role of DHA in neural development. Eur J Lipid Sci Technol.
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