Studies have shown an association between maternal fatty acid intake and pregnancy outcomes, including birth weight, birth length and gestational age, due to foetal development being entirely dependent on essential fatty acid supply from the mother.
However, the mechanisms behind the correlation between maternal fatty acid intake and foetal size are have not been fully understood.
Input versus output
As such, researchers at Ewha Woman's University and Seoul National University conducted a study to determine the link between maternal fatty acid intake and birth outcomes among pregnant women who were subjects in the Mothers and Children’s Environmental Health (MOCEH) prospective cohort study in South Korea.
Between August 2006 and December 2010, they recruited a total of 1,407 pregnant women aged 30 to 34 at 12 to 28 weeks' gestation, monitoring their dietary intake using the one-day, 24-hour recall method.
The researchers also analysed the pregnancy outcome data (infants' gestational age, birth weights and birth length) in relation to the women's fatty acid intake.
They then observed that after adjustment for confounding factors, high maternal intake of omega-6 fatty acids were correlated with adverse effects on birth weight and length.
Multiple regression analysis showed that the odds ratio for the risk of birth weight being among the lowest 10% was higher for the infants whose mothers were among the top 20% of participants in terms of omega-6 intake, compared to those whose mothers were among the bottom 20%.
In addition, the odds ratio for birth length being among the top 10% was lower for the infants whose mothers' omega-6 intake put them in the top 20% of participants, as opposed to those whose mothers were in the bottom 20%.
External and internal factors
However, the researchers found no correlation between maternal omega-3 intake and birth weight or birth length.
They also listed several limitations of the study: firstly, it was difficult to accurately calculate the participants' daily intake due to the one-day, 24-hour recall survey used.
Secondly, the impact of fatty acid supplementation was not included in the results, due to insufficient data on products containing omega-3 and omega-6. Over 50% of the participants were taking a variety of supplements, with only 3% consuming supplements containing omega-3 and / or omega-6.
As omega-3 supplementation (such as with DHA) can influence pregnancy outcomes, the researchers wrote that more studies are required to explore the impact of omega-3 supplementation.
Lastly, the participants' plasma omega-3 and omega-6 levels were not measured. This could have explained the link between maternal omega-6 intake and birth weight and length, a factor the researchers said would need to be considered in future studies.
They concluded: "This study was the first to investigate the relationship between the intake of fatty acids and pregnancy outcome among pregnant women in Korea. Despite adequate levels of omega-3 fatty acids, women who had high levels of omega-6 fatty acids tended to have lower birth weight infants.
"Therefore, reducing excessive omega-6 fatty acid intake of pregnant women in Korea will improve maternal nutritional status and also have more positive outcomes of pregnancy."
Source: Nutrition Journal
"Association of maternal omega-6 fatty acid intake with infant birth outcomes: Korean Mothers and Children’s Environmental Health (MOCEH)"
Authors: Eunjung Lee, et al.