DHA & Brain Development in Pregnancy: Key Facts

ByRohan Smith
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 serves as a primary structural component of fetal brain tissue. During pregnancy, DHA is preferentially transferred across the placenta and incorporated into neuronal cell membranes, where it may support synaptogenesis, myelination, and retinal development. Research published in Progress in Lipid Research and the American Journal of Clinical Nutrition suggests that inadequate maternal DHA intake is associated with less optimal neurodevelopmental outcomes, making dietary intake during pregnancy clinically important (1-6).

At a Glance

  • DHA constitutes approximately 10-15% of total fatty acids in the human cerebral cortex and is the most abundant omega-3 fatty acid in the brain (1,2).
  • Placental transfer of DHA increases substantially during the third trimester, coinciding with rapid cortical development and synaptogenesis (4,5).
  • A 2018 Cochrane systematic review by Middleton et al. found that omega-3 supplementation during pregnancy may reduce the risk of preterm birth (18).
  • Algal oil supplements provide a mercury-free source of preformed DHA suitable for vegetarian and vegan pregnant individuals (17).
  • The European Food Safety Authority (EFSA) recommends an additional 100-200 mg of DHA per day during pregnancy beyond standard adult omega-3 intake (16).

What Is DHA?

DHA (docosahexaenoic acid) is a 22-carbon polyunsaturated omega-3 fatty acid that constitutes the most abundant long-chain polyunsaturated fatty acid (LC-PUFA) in the human brain, retina, and central nervous system. As described by Stillwell and Wassall in Chemistry and Physics of Lipids, DHA forms a key component of neuronal cell membrane phospholipids, where it influences membrane fluidity, synaptic vesicle function, and signal transduction between nerve cells (1,2).

Unlike shorter-chain omega-3 precursors such as alpha-linolenic acid (ALA), DHA cannot be synthesised efficiently in sufficient quantities through the delta-6 desaturase and elongase enzymatic pathway. As a result, adequate levels depend largely on dietary intake, particularly from marine-based sources such as fatty fish and algae (3).

The Role of DHA in Fetal Brain Development

Maternal-Fetal Transfer

Placental DHA transport occurs via specific fatty acid transport proteins (FATPs) and fatty acid binding proteins (FABPs) that preferentially shuttle DHA from maternal circulation to the fetus. Research by Lauritzen et al. in Progress in Lipid Research demonstrates that this transfer increases substantially during the third trimester, a critical period characterised by rapid fetal brain growth, cortical folding, and expansion of grey matter volume (4,5).

Neuronal Structure and Function

DHA contributes to several foundational processes in neurodevelopment. Crawford et al. documented DHA’s role in these processes in the European Journal of Lipid Science and Technology:

Neurodevelopmental Process Role of DHA
Neuronal membrane integrity Maintains phospholipid bilayer fluidity and flexibility, enabling receptor function
Synaptogenesis Supports synapse formation and dendritic branching in the developing cortex
Myelination Contributes to myelin sheath composition, enhancing neural signal transmission speed
Neuroprotectin D1 (NPD1) synthesis DHA-derived docosanoid that may protect neurons from oxidative stress and apoptosis

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

DHA and Cognitive Outcomes

Prenatal DHA exposure has been associated with aspects of early cognitive development in multiple observational and interventional studies. Colombo et al., publishing in the American Journal of Clinical Nutrition (2019), reported associations between maternal DHA status and infant attention, visual acuity measured by Teller acuity cards, and problem-solving ability on the Bayley Scales of Infant Development. Outcomes vary depending on factors such as dosage, timing of exposure, and baseline maternal DHA status (9-11).

Oken et al. in a cohort from Project Viva found that lower maternal DHA levels during pregnancy were 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

Omega-3 polyunsaturated fatty acids, particularly DHA, modulate serotonergic and dopaminergic neurotransmission and regulate neuroinflammatory pathways including the NF-kB signalling cascade. Markhus et al. in the Journal of Affective Disorders found that lower omega-3 and DHA status was 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 including genetic polymorphisms in the FADS gene cluster (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. Bazinet and Laye’s review in Nature Reviews Neuroscience further supports the role of polyunsaturated fatty acid metabolites in brain function and disease (14).

How to Support Adequate DHA Intake

Dietary Sources

Fatty fish represent the most concentrated dietary source of preformed DHA. The European Food Safety Authority (EFSA) and Koletzko et al. in the British Journal of Nutrition recommend consuming low-mercury fish two to three times per week during pregnancy to support omega-3 intake (16,19).

Food Source DHA Content (approx. per 100g) Mercury Risk
Atlantic salmon 1,200-1,500 mg Low
Sardines 700-1,000 mg Very low
Rainbow trout 500-800 mg Low
Atlantic mackerel 600-1,000 mg Low-moderate
DHA-fortified eggs 50-150 mg None

Supplementation

For individuals who avoid fish or have increased nutritional requirements, DHA supplements — particularly those derived from algal oil (sourced from the microalgae Schizochytrium sp.) — offer a direct source of DHA without methylmercury exposure. The DOMInO trial led by Makrides et al., published in JAMA (2010), examined DHA supplementation during pregnancy and its effects on maternal depression and child neurodevelopment (17,18).

Fortified Foods

Some eggs and dairy products are fortified with DHA through microalgae-enriched feed and can make a modest contribution to overall intake. However, these foods typically provide 50-150 mg per serving and are unlikely to meet the recommended 200-300 mg DHA per day on their own (19).

When DHA Intake May Require Closer Attention

Risk Factor Reason for Concern
Low or absent fish and seafood consumption Primary dietary DHA source is eliminated
Vegetarian or vegan dietary patterns Plant-based ALA conversion to DHA is typically less than 5%
Multiple or closely spaced pregnancies Maternal DHA stores may become progressively depleted
Fat malabsorption or gut health disorders Impaired absorption of dietary long-chain fatty acids

In these contexts, individualised nutritional assessment including erythrocyte fatty acid profiling (the Omega-3 Index) may be appropriate (20).

Next Steps

  1. Assess your current DHA intake: Consider whether your diet regularly includes fatty fish or other reliable DHA sources.
  2. Discuss supplementation: If dietary intake is insufficient, speak with a practitioner about algal oil or fish oil supplementation appropriate for pregnancy.
  3. Seek personalised guidance: If you have dietary restrictions, gut health concerns, or multiple pregnancies, individualised nutritional assessment can help ensure adequate DHA status.

Frequently Asked Questions

Why is DHA important during pregnancy?
DHA is a structural component of the developing brain and nervous system. During pregnancy, it is actively transferred from mother to fetus, particularly in the third trimester, supporting brain growth, neural signalling, and visual development.

Can the body make enough DHA on its own during pregnancy?
The body has a limited ability to convert other omega-3 fats (such as ALA) into DHA via the delta-6 desaturase pathway, with conversion rates typically below 5%. For most people, adequate DHA levels depend largely on dietary intake from fish or direct DHA supplementation.

Who may be at higher risk of low DHA intake during pregnancy?
Individuals who consume little or no seafood, follow vegetarian or vegan diets, have closely spaced pregnancies, or experience fat malabsorption or gut health issues may require closer attention to DHA intake. Erythrocyte fatty acid testing (Omega-3 Index) can help assess individual status.

Key Insights

  • 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
  • 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

Citable Takeaways

  1. DHA constitutes approximately 10-15% of total fatty acids in the human cerebral cortex and is the most abundant omega-3 in brain tissue, according to Stillwell and Wassall in Chemistry and Physics of Lipids (2003) (1).
  2. Placental DHA transfer increases substantially during the third trimester via fatty acid transport proteins, coinciding with rapid cortical development, as reported by Lauritzen et al. in Progress in Lipid Research (2001) (4).
  3. The Cochrane systematic review by Middleton et al. (2018) found that omega-3 fatty acid supplementation during pregnancy may reduce the risk of preterm birth (18).
  4. The EFSA recommends an additional 100-200 mg DHA per day during pregnancy beyond standard adult omega-3 requirements, as published in EFSA Journal (2010) (16).
  5. Conversion of the plant-based precursor alpha-linolenic acid (ALA) to DHA is typically less than 5% in humans, making preformed dietary DHA from fish or algal sources clinically important during pregnancy (3).
  6. Oken et al. in Epidemiology (2008) found that higher maternal fish intake during pregnancy was associated with improved child cognition and behaviour outcomes in the Project Viva cohort (12).

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 and ensure key nutrients are adequately supported for both maternal health and fetal development.

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References

  1. Stillwell W, Wassall SR. Docosahexaenoic acid: membrane properties of a unique fatty acid. Chem Phys Lipids. 2003 Nov;126(1):1-27. https://doi.org/10.1016/S0009-3084(03)00098-6
  2. Salem N Jr et al. Mechanisms of action of docosahexaenoic acid in the nervous system. Lipids. 2001 Sep;36(9):945-59. https://doi.org/10.1007/s11745-001-0805-6
  3. Brenna JT et al. Docosahexaenoic and arachidonic acid concentrations in human breast milk worldwide. Am J Clin Nutr. 2007 Jun;85(6):1457-64. https://doi.org/10.1093/ajcn/85.6.1457
  4. Lauritzen L et al. The essentiality of long-chain n-3 fatty acids for brain and retinal development. Prog Lipid Res. 2001 Jan;40(1-2):1-94. https://doi.org/10.1016/S0163-7827(00)00008-6
  5. Innis SM. Impact of maternal diet on human milk composition and neurological development of infants. Am J Clin Nutr. 2014 Mar;99(3):734S-741S. https://doi.org/10.3945/ajcn.113.072595
  6. Martinez M. Tissue levels of polyunsaturated fatty acids during early human development. J Pediatr. 1992 Mar;120(3 Pt 2):S129-38. https://doi.org/10.1016/s0022-3476(05)81247-5
  7. Crawford MA et al. The role of DHA in neural development. Eur J Lipid Sci Technol. 2003;105(5-6):281-287. https://doi.org/10.1002/ejlt.200390057
  8. Carlson SE. Docosahexaenoic acid and arachidonic acid in infant development. Semin Neonatol. 2001 Oct;6(5):421-8. https://doi.org/10.1053/siny.2001.0091
  9. Colombo J et al. Long-chain polyunsaturated fatty acid supplementation in infancy: neurodevelopmental outcomes. Am J Clin Nutr. 2019 Mar;109(3):630-639. https://doi.org/10.1093/ajcn/nqy311
  10. Gould JF et al. DHA supplementation during pregnancy and childhood cognitive outcomes: a systematic review and meta-analysis. Am J Clin Nutr. 2014 Mar;99(3):742-51. https://doi.org/10.3945/ajcn.113.070417
  11. Campoy C et al. Effects of docosahexaenoic acid supplementation on neurodevelopment in preterm infants: a randomized controlled trial. Br J Nutr. 2010;104(11):1629-37. https://doi.org/10.1017/S0007114510002569
  12. Oken E et al. Maternal fish intake during pregnancy, child cognition, and behavior. Epidemiology. 2008 May;19(3):409-17. https://doi.org/10.1097/EDE.0b013e31816b3b1a
  13. Hibbeln JR et al. Maternal seafood consumption in pregnancy and neurodevelopmental outcomes in childhood (ALSPAC study): an observational cohort study. Lancet. 2007 Feb 17;369(9561):578-85. https://doi.org/10.1016/S0140-6736(07)60277-3
  14. Bazinet RP, Laye S. Polyunsaturated fatty acids and their metabolites in brain function and disease. Nat Rev Neurosci. 2014 Dec;15(12):771-85. https://doi.org/10.1038/nrn3820
  15. Markhus MW et al. Omega-3 fatty acids and maternal mental health. J Affect Disord. 2019;245:104-111. https://doi.org/10.1016/j.jad.2018.11.042
  16. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). Scientific opinion on dietary reference values for fats. EFSA Journal. 2010;8(3):1461. https://doi.org/10.2903/j.efsa.2010.1461
  17. Makrides M et al. Effect of DHA supplementation during pregnancy on maternal depression and neurodevelopment of young children: a randomized controlled trial. JAMA. 2010 Oct 20;304(15):1675-83. https://doi.org/10.1001/jama.2010.1507
  18. Middleton P et al. Omega-3 fatty acid addition during pregnancy. Cochrane Database Syst Rev. 2018 Nov 15;11(11):CD003402. https://doi.org/10.1002/14651858.CD003402.pub3
  19. Koletzko B et al. Dietary fat intakes for pregnant and lactating women. Br J Nutr. 2007 Dec;98(6):1241-50. https://doi.org/10.1017/S0007114507831726
  20. Innis SM, Friesen RW. Essential n-3 fatty acids in pregnant women and early visual acuity maturation in term infants. Am J Clin Nutr. 2008 Mar;87(3):548-57. https://doi.org/10.1093/ajcn/87.3.548

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