Longer pregnancies & bigger babies: RCT supports omega-3s birth weight benefits for babies

By Stephen Daniells contact

- Last updated on GMT

© Getty Images / RodicaCiorba
© Getty Images / RodicaCiorba
Consumption of fish oil omega-3s during the third trimester of pregnancy may prolong gestation and increase birth weights of the newborns, according to a new double-blind randomized controlled trial.

Data published in the The Journal of Nutrition​ indicated that supplementation with marine-sourced eicosapentaenoic acid (EPA, C20:5 n-3) and docosahexaenoic acid (DHA, C22:6 n-3) at a dose of 2.4 grams per day during the third trimester led to an average prolongation in pregnancy of two days.

In addition, the omega-3s supplementation was associated with a 97 gram higher birth weight in the infants, reported scientists from the University of Copenhagen, the University of Gothenburg, and the Norwegian Institute of Public Health.

“In this RCT, we have confirmed earlier findings showing that fish-oil supplementation during pregnancy leads to a prolongation of pregnancy and an increase in birth weight,” ​they wrote.

“Furthermore, we demonstrate a significantly larger size for [gestational age] in the n–3 [long-chain polyunsaturated fatty acids]–supplemented group. This suggests that the increase in birth weight is not solely explained by the prolonged duration of pregnancy, but is also a consequence of increased intrauterine growth. To our knowledge this has not been shown before.”

Health benefits and healthcare cost savings

The study adds to a growing body of science supporting the benefits of omega-3 supplementation on pregnancy and the health and development of the infants.

Data from the Kansas University DHA Outcomes Study (KUDOS)​ indicated that universal supplementation with DHA (600 mg per day) during the last two trimesters of pregnancy led to significant reductions in early preterm birth. This would result in cost savings of $1,678 per infant. Taking out the $166.48 cost of the DHA supplements for 26 weeks and a $26 increase in maternal care costs, the net saving became $1,484.

For the nearly 4 million live births in the US every year this cost saving would become almost $6 million, reported the researchers in a study titled Prostaglandins, Leukotrienes and Essential Fatty Acids​.

However, the new study in The Journal of Nutrition​ did not have sufficient statistical power to demonstrate a reduction in preterm delivery or the birth of small children for their gestational age, noted the researchers.

“The results corroborate the benefits of supplementary EPA/DHA during pregnancy”

Commenting independently on the study’s findings, Harry Rice, PhD, VP of regulatory & scientific affairs for the Global Organization for EPA and DHA Omega-3s (GOED), told us: “At the risk of discounting the co-authors efforts and positive findings, very little new is being reported.

“Quite simply, the results corroborate the benefits of supplementary EPA/DHA during pregnancy and public policy needs to embrace the consistently positive data. From a public health perspective, it's unconscionable to not have an omega-3 recommendation for pregnant women.”​  

Study details

Omega-3 Fish oil © Getty Images areeya_ann
© Getty Images / areeya_ann

The researchers recruited 736 women between weeks 22 and 26 of their pregnancies to participate in the double-blind randomized controlled trial. The women were randomly assigned to consume supplements containing four grams of fish oil per day providing 2.4 grams of omega-3 (55% EPA and 37% DHA, Incromega TG33/22; Croda Health Care) or a control (olive oil) until one week after birth.

Results showed that, in addition to the increases in the duration of pregnancy and birth weight, an increase in gestation age was also recorded by the researchers.

“Fish oil supplementation during the third trimester of pregnancy led to a prolongation of gestation and a higher birth weight,”​ wrote the researchers.

“The increase in birth weight was due to an increase in pregnancy duration and likely an increased intrauterine growth, because we found an increase in size for [gestational age].

“Future studies should focus on dose-response relations and the composition of n–3 LCPUFAs in fish oil supplementation as well as the overall potential for improving fetal and infant health.”

Source: The Journal of Nutrition
Published online ahead of press, doi: 10.1093/jn/nxy204
“Fish Oil Supplementation in Pregnancy Increases Gestational Age, Size for Gestational Age, and Birth Weight in Infants: A Randomized Controlled Trial”
Authors: R. Kofod Vinding  et al.

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