Omega-3 supplements in early pregnancy may boost foetal growth: RCT

By Nicola Gordon-Seymour

- Last updated on GMT

Omega-3 supplementation during pregnancy has been found to reduce the risk of preterm birth.   Image © onairjiw / Getty Images
Omega-3 supplementation during pregnancy has been found to reduce the risk of preterm birth. Image © onairjiw / Getty Images

Related tags omega-3 Dha Epa Omega-3 fatty acid Pregnancy

Maternal supplementation with docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in early pregnancy could bolster foetal growth in later stages and improve neonatal biometrics, according to a US study.

Prior research has established an association between prenatal maternal consumption of  DHA/EPA and longer gestation and higher birth weight but outcomes relating to specific neonatal anthropometrics (such as length and head circumference) are inconsistent, say the authors of a new study published in the American Journal of Obstetrics and Gynaecology​.

Researchers therefore set out to establish a link between first trimester gestational DHA/EPA consumption and foetal biometric measures during a five-month period and discovered significant growth improvements in foetal abdominal circumference (AC) and AC to head circumference (HC) ratio.

“Intriguing, but…”

Vice President of Regulatory and Scientific Affairs at the Global Organisation for EPA and DHA (GOED), Harry Rice, recognises the novel objective of the study and describes the results as “intriguing​” but “underwhelming​” as he believes they raise “too many unanswered questions​”.

“The reality is that this was an exploratory analysis and requires additional research to confirm what I would call preliminary results.”

Furthermore, he asserts the main strength of evidence supporting supplementation lies in the ability of omega-3 to reduce the risk of preterm birth and asserts this should be the main focus of public policy.

Study programme

The study cohort comprised a cross-section of 1,535 racially mixed, low-risk pregnant women recruited from 12 clinics across the US.

Participants were enrolled at eight to 12 weeks of gestation and randomised to one of four follow-up visit schedules, comprising five visits in total, to identify demographic, health, and lifestyle characteristics.

Average dietary DHA/EPA consumption (grams/day) in the periconception and first trimester was calculated using information from self-administered food frequency questionnaires. Women who reported no first trimester supplementation were categorized based on whether they met the recommended intake 0.25 g/d of dietary DHA/EPA (from supplements or dietary sources).

Dietary intake data was collected to determine foetal growth in first trimester DHA/EPA supplementation. Foetal ultrasonographic measurements were noted for abdominal circumference (AC), biparietal diameter (BPD), femur length (FL), and head circumference (HC), and humerus length (HL) at enrolment (8-13 weeks) and five follow-up visits. Estimated foetal weight (EFW) and HC:AC ratio (a measure of growth symmetry) was also calculated.

Weekly comparison tests were also performed where global differences were significant to evaluate foetal growth parameters, excluding pre-term birth.

Clinical significance

Researchers noted significant differences in foetal development as a result of DHA/EPA consumption. Maternal intake resulted in improved EFW, AC, HC, and HC to AC ratio.

EFW was consistently higher in women taking supplementation starting from week 19 and were statistically significant by the end of pregnancy, with foetal weight 83 to 134 grams greater than the control between 38 and 41 weeks.

Similarly, analyses revealed significant increases in the biometric measurements for AC in the second trimester (17 weeks) and HC in the third trimester (30 weeks). A smaller HC to AC ratio in mid and late pregnancy, compared with women without supplementation was also observed.

Foetal BPD in women consuming 0.25g/d or higher of dietary DHA/EPA was greater at term, compared to women taking less than 0.25g/d. Consumption was also linked to significantly lower risk of small gestational age (SGA). There was no difference in gestational duration with DHA/EPA intake.

The authors’ commented: “Although these are small differences of uncertain clinical significance, the increasing trends in foetal growth, especially the increase in EFW and AC in response to  DHA/EPA supplementation, generate interesting hypotheses.”

Positive trends

Researchers acknowledged the study limitations, which include lack of information on dose, frequency, and duration of supplement intake before or during pregnancy.

In addition, differences in foetal growth may relate to overall maternal lifestyle and the small disparity among groups make it impossible to formulate conclusions about the clinical implications of findings.

They added that given the observational nature of this study, “causality cannot be known”​ but positive trends can be applied to inform future research.

Source: American Journal of Obstetrics and Gynaecology
Published online August 5, 2022:
‘The association between first trimester omega-3 fatty acid supplementation and fetal growth trajectories’
Authors: Y. Vafai, et al.

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