Research published in the Journal of Perinatology last week adds another layer of substantiation to setting an appropriate omega-3 DHA level for pregnant women.
This prospective cohort study took place between February and August 2016 at the Obstetrics and Gynecology Department of the Citadelle Regional Hospital Center, Liège, Belgium.
The researchers studied 108 healthy women with a singleton pregnancy. Gestational length, birth anthropometric measures, and pregnancy-associated complications were collected from hospital medical records, as was data on their red blood cell omega-3 levels (i.e., Omega-3 Index).
The authors of this study say the interest in the role of omega-3 fatty acids on pregnancy outcomes began in the early 1980s, when researchers observed longer gestation, higher birth weight, and less preterm birth (PTB) in the fish-eating community of the Faroe Islands compared to those in Denmark.
“Evidence is now accumulating that the availability of nutrients prior to and during the first trimester of pregnancy influences fetal development in ways that affect the lifetime health of the offspring,” the study authors noted. “This time point, however, remains under-studied when considering the effects of fatty acids exposure on the health of both the mother and child.”
This is because many previous observational studies were restricted to relationships with maternal fatty acid exposure in late pregnancy, but recent evidence suggests that maternal fatty acid exposure as soon as the early stages of pregnancy could also affect fetal growth and maternal mental health in a positive way.
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Preterm birth and fetal growth restriction remain major obstetric healthcare problems and significant risk factors for perinatal morbidity, mortality, and long-term disability. The researchers in this paper say while perinatal and neonatal care have improved markedly, prevention strategies have the potential to make significant impact on pregnancy complication rates, and that continued progress in such areas is warranted and could be one of the highest priorities in contemporary healthcare.
As such, this prospective study aimed to contribute to the evidence base for primary prevention. “We found that higher DHA levels and omega-3 index values were associated with longer length of gestation, higher birth weight, and larger head circumference,” researchers said in their paper. “By contrast, we found that a higher omega-6/omega-3 ratio was associated with shorter length of gestation and lower birth weight.”
Among the long-chain derivatives, the researchers in this study point out that DHA has received particular attention in the last 10 years for the prevention of spontaneous delivery, leading some researchers to propose a target prenatal DHA level. OmegaQuant’s Dr. Kristina Harris Jackson is one of those researchers who proposed a target DHA level in a paper she published in December 2018.
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For the future, the authors of this study feel personalized nutrition could offer new opportunities, in particular for the dietary management of those who need special nutritional support such as pregnant women. In other words, helping women establish their baseline DHA level and striving to meet the optimal level of 5% could guide the appropriate intake of DHA and potentially improve pregnancy outcomes like preterm birth.
Because the quality of lipids has undergone major changes in the last 50 years, the authors of this study further concluded that prenatal counseling should spread awareness of the importance of omega-3s during pregnancy.
The ORIP Study – Encouraging a Targeted Approach for DHA Supplementation
Last September, a study published in the New England Journal of Medicine showed that those who have the lowest omega-3 DHA levels might benefit the most from supplementation when it comes to reducing their preterm birth risk.
Called the ORIP Trial (Omega-3 fats to Reduce the Incidence of Prematurity), the purpose of the study was to investigate whether taking a fish oil rich in the omega-3 fat DHA could help prevent very premature delivery (before 34 weeks).
The high level results showed that DHA supplementation had no effect on early preterm birth, especially for those already getting a fair amount of DHA in their diet or through supplementation.
Studying ~5400 Australian women, ORIP is the largest clinical trial of omega-3 supplementation during pregnancy in the world. And given the weight of these results, it warrants further exploration on why there wasn’t a significant reduction in early preterm birth.
Approximately 80% of Australian women now consume perinatal supplements, many of which contain small doses of DHA. Although the researchers in the ORIP study excluded women who were taking more than 150 mg of DHA per day, they enrolled more than 700 women who were known to have been regularly consuming a low dose of DHA (≤150 mg per day).
As a result, this may have influenced the baseline level of DHA among the women included in the ORIP trial, which was about 20% higher than that observed in the Kansas University DHA Outcomes Study (KUDOS), in which a significantly lower rate of early preterm delivery was observed with omega-3 supplementation than with placebo.
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ORIP researchers said it is possible that women with low omega-3 status are the ones most likely to benefit from dietary supplementation strategies; however, they did not find evidence to support this hypothesis in the prespecified subgroup analysis they performed according to baseline DHA status. To that end, they believe further study is needed to determine whether there may be benefit in women who have low omega-3 levels.
According to OmegaQuant’s Dr. Jackson, blood levels in the ORIP study were 4.5% DHA (keep in mind that an ideal DHA target level is 5%) at baseline for both groups; at 34 weeks, the omega-3 group went up to 5.1% vs. 4.1% in the control group.
“We converted their DHA level from whole blood to RBC values,” Dr. Jackson said. “With 900 mg per day DHA, I’m very surprised levels didn’t increase more than 0.6%. In a study where women were given 200 mg per day of DHA for 10 weeks starting in the third trimester, DHA RBC levels went from 5.3% to 6.4% (~1.1%). Was compliance an issue?”
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Another difference Dr. Jackson pointed out was that the researchers stopped supplementation at 34 weeks to avoid increasing post-term interventions. In most other studies, however, supplementation was continued until birth. “This could have affected the outcomes,” she said. “Also, 6-8 weeks of no supplemental DHA during perhaps the most critical stage of pregnancy as far as fat and DHA transfer to the fetus is concerned is troubling.”
Further, Dr. Jackson noted that the lowest 25th percentile of women had RBC DHA levels of <3.99%; the highest 25th percentile was >5%. This matches fairly well with our assessment that ~80% of women are <5%.
Also, in the study’s supplemental materials, it was shown that early preterm birth rates trend with baseline blood levels (Quartiles 1-4, lowest to highest RBC DHA), so that those with higher DHA at baseline had lower preterm birth rates. Baseline levels didn’t affect the supplemented group and supplementation appears to not be helping women with high baseline levels.
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One BIG caveat for the ORIP study, Dr. Jackson said, is that they included women with multiple fetuses (twins+). “This is highly unusual for these kinds of studies because twins are known to affect gestational period,” she said. “Olsen et al. 2007 found that 2.7 grams per day of fish oil didn’t do anything to elongate the gestational period for twins.
Furthermore, most studies in last year’s Cochrane Review excluded twins from recruitment. In supplementary analyses of ORIP there is a significant effect on preterm birth rates in women with singleton births only.
“I can’t imagine that 900 mg per day of DHA is not high enough for the general pregnant population,” Dr. Jackson stated. “I still think 200-300 mg per day of DHA is a good target intake, especially for those with low DHA levels. How blood levels and supplementation are interacting in this study is difficult to explain.”
The Importance of Personalizing DHA Intake
A year ago, we launched the Prenatal DHA Test for pregnant women and their doctors as a way to guide the appropriate intake of DHA during before and during pregnancy. It simply measures the amount of DHA in the blood, with a 5% target being the most protective level. Following pregnancy, women can further monitor their DHA intake in both blood and/or breastmilk (using the Mother’s Milk DHA Test).
These objective measurements of DHA status can help women and their doctors measure, modify and monitor their status, so that they continue to consume enough of this important nutrient from pregnancy through lactation and well into the postpartum period.