Omega-3, pregnancy and preterm birth

Omega-3, pregnancy and preterm birth

Preterm birth (birth before 37 weeks gestation) is leading cause of neonatal mortality. Infants born preterm generally require care in neonatal intensive care, and can have an increased risk of a number of potentially serious complications such as cerebral palsy, respiratory distress syndrome, intraventricular haemorrhage, necrotising enterocolitis and blindness. Preterm birth cannot be easily predicted, however we can do everything in our power to prevent it.

Nutritional status during and prior to pregnancy is an important determinant of fetal health through pregnancy. Observations of populations with higher fish consumption found increased lengths in gestation. So what does fish have that potentially decreases risk of preterm birth? Fish is high in an essential fatty acid, omega-3. Omega-3 is hard to come by in any other food source, so our friends in the sea are one of the only places we can find it. There are a few omega-3’s:

  • Eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA): found almost exclusively in oily fish and seafood.
  • A-linoleic acid (ALA): found in some nuts, linseed and canola oil, legumes and small amounts in leafy greens. ALA is generally inactive until converted to EPA and DHA, of which it only converts very small amounts.

Omega-3’s, specifically EPA and DHA play key roles in the development of the fetus, modulating inflammation and the synthesises of prostaglandins. Prostaglandins are substances that play a role in blood flow, the induction of labour and gestational length through reducing the inflammatory pathway which is linked to spontaneous preterm birth. During labour omega-3’s play a crucial role in the inflammatory cascade, blood flow and cervical ripening.

In fetal development, omega-3’s have been shown to impact the fetal brain, retina and respiratory system. Higher near-birth DHA levels in the fetus are associated with increases in brain volume that correlate with increased language and motor scores in preschool age children. Supplementation during pregnancy reduces the incidence of asthma and improves heart rate variability, with low levels of omega-3 through childhood being postulated to be a risk factor for autism spectrum disorder.

So how do I get omega 3?

  • Intake of fatty fish – especially sustainably wild sourced and of a good quality.
  • Supplement a good quality fish oil, that is rich in DHA. Poor quality fish oils can be contaminated with heavy metals, come from low quality processing facilities and may even be rancid. Quality is everything with omega-3 supplementation.
  • Some omega-3 can be from a marine algal source, which can also be excellent – just ensure that this is a high EPA/DHA marine algae.

How much do I take?

There have been a lot of studies on supplementation in pregnant women with doses of 750-1000mg/day shown to be safe and effective.

Although there are studies on omega-3 and fish oil supplements being safe and effective for most pregnant women, always consult with your healthcare professional before starting any new supplements. There can never be a guarantee that any one supplement will prevent preterm birth for your specific situation. There is no one size fits all approach to pregnancy care, always have a team of professionals assessing your nutrition, supplements and lifestyle.

Further reading:

  1. Olsen SF, Halldorsson TI, Thorne-Lyman AL, Strøm M, Gørtz S, Granstrøm C, et. al, Plasma  Concentrations of Long Chain N-3 Fatty Acids in Early and Mid-Pregnancy and Risk of Early Preterm Birth, 2018, eBioMedicine, 2018 Sep 01, 35(2018);325-333, DOI:
  2. Lizewska B,  Teul J,  Kuc P, Lemancewicz A, Charkiewicz A, Goscik J, et al., Maternal Plasma Metabolomic Profiles in Spontaneous Preterm Birth: Preliminary Results, Mediators of inflammation, 2018; 1-13,
  3. Makrides M, Best K: Docosahexaenoic Acid and Preterm Birth. Ann Nutr Metab, 2016 Nov 01, 69(suppl 1);29-34.
  4. Ramakrishnan U, Stein AD, Parra-Cabrera S, et al. Effects of Docosahexaenoic Acid Supplementation During Pregnancy on Gestational Age and Size at Birth: Randomized, Double-Blind, Placebo-Controlled Trial in Mexico. Food and Nutrition Bulletin. 2010;31(2_suppl2):S108-S116. doi:10.1177/15648265100312S203
  5. National Health and Medical Research Council, Australian Government Department of Health and Ageing, New Zealand Ministry of Health. Nutrient Reference Values for Australia and New Zealand. Canberra: 2006 National Health and Medical Research Council; (cited 2021 April 4); 31p. Available from:
  6. Imhoff‐Kunsch B, Briggs V, Goldenberg T, Ramakrishnan U, Effect of n‐3 Long‐chain Polyunsaturated Fatty Acid Intake during Pregnancy on Maternal, Infant, and Child Health Outcomes: A Systematic Review. Paediatric and Perinatal Epidemiology, 2012(26); 91-107.
  7. Makrides M, Gibson RA, McPhee AJ, et al. Effect of DHA Supplementation During Pregnancy on Maternal Depression and Neurodevelopment of Young Children: A Randomized Controlled Trial. JAMA. 2010;304(15):1675–1683. doi:10.1001/jama.2010.1507
  8. Carlson SE, Gajewski BJ, Valentine CJ et al. Assessment of DHA on reducing early preterm birth: the ADORE randomized controlled trial protocol. BMC Pregnancy Childbirth 2017, 17(62):1-16,
  9. Kamino D, Studholme C, Liu M, Chau V, Miller SP, Synnes A, et al., Postnatal polyunsaturated fatty acids associated with larger preterm brain tissue volumes and better outcomes. Pediatr Res. 2018 Jan;83(1-1):93-101. doi: 10.1038/pr.2017.230.
  10. Carlson SE, Colombo J, Gajewski BJ, Gustafson KM, Mundy D, Yeast J, et al., DHA supplementation and pregnancy outcomes, The American Journal of Clinical Nutrition, 2013 Apr; 97(4):808–815,
  11. Olsen SF, Secher NJ, Tabor A, Weber T, Walker JJ, Gluud C. Randomised clinical trials of fish oil supplementation in high risk pregnancies. Fish Oil Trials In Pregnancy (FOTIP) Team. BJOG. 2000 Mar;107(3):382-95. doi: 10.1111/j.1471-0528.2000.tb13235.x. PMID: 10740336.
  12. Oken E, Kleinman KP, Olsen SF, Rich-Edwards JW, Gillman MW, Associations of Seafood and Elongated n-3 Fatty Acid Intake with Fetal Growth and Length of Gestation: Results from a US Pregnancy Cohort, American Journal of Epidemiology, 2004 Oct 15;160(8):774–783,
  13. Harper M, Thom E, Klebanoff MA, Thorp J Jr, Sorokin Y, Varner MW, National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. Omega-3 fatty acid supplementation to prevent recurrent preterm birth: a randomized controlled trial. Obstet Gynecol. 2010 Feb;115(2 Pt 1):234-242. doi: 10.1097/AOG.0b013e3181cbd60e
  14. Middleton  P, Gomersall  JC, Gould  JF, Shepherd  E, Olsen  SF, Makrides  M. Omega‐3 fatty acid addition during pregnancy. Cochrane Database of Systematic Reviews 2018, Issue 11. DOI: 10.1002/14651858.CD003402.pub3.
  15. Ahmed S, Middleton P, Gomersall JC, Gould JF, Shepherd E, Olsen SF, Makrides M. Omega-3 fatty acid addition during pregnancy. Cochrane Database Syst Rev. 2018 Nov 15;11(11):CD003402. doi: 10.1002/14651858.CD003402.
  16. Leventakou V, Roumeliotaki T, Martinez D, Barros H, Brantsaeter A-L, Casas M, et al., Fish intake during pregnancy, fetal growth, and gestational length in 19 European birth cohort studies, The American Journal of Clinical Nutrition, 2014 Mar, 99(3):506–516,

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