Gynecology and obstetrics

HS-Omega-3 Index and building the brain in pregnancy

DHA is the most important structural fatty acid in brain and eye. Daily some 75 mg DHA are pumped across the placenta to build up the fetus’ brain and eyes in the last three months of pregnancy at the mothers expense (Brenna u. Carlson, 2014). Specific proteins in the placenta actively and selectively transport DHA (Dunstan et al, 2004, Larqué et al, 2011). According to in vivo kinetics, this transport of DHA is regulated, so that DHA will reach approximately 9% in fetal erythrocytes, with EPA accounting for another 1.5 to 2.5% (Dunstan et al, 2004). Many scientific societies recommend a daily intake of at least 200 mg DHA during pregnancy (; Koletzko et al 2008). The recommendation supports an adequate brain structure, and adequate complex brain function (details below). The scientific societies recommend to diagnose deficits in nutrition early in pregnancy and act upon the results.

According to our measurements, more than 75% of the population have a HS-Omega-3 Index below the target range of 8 – 11% (von Schacky, 2014), which also applies to pregnant women. Therefore, we think that the HS-Omega-3 Index should be determined before or early in pregnancy, in order to detect a deficit in EPA and/or DHA. There is a substantial body of evidence demonstrating that pregnancies without a deficit in EPA and/or DHA have a better course and a better outcome for mother and child. This body of evidence is based on randomized intervention trials with EPA and/or DHA in pregnant women, and will be briefly presented here.

Duration of pregnancy and childbed

Duration of pregnancy: A systematic analysis of randomized intervention trials, comprising 1278 newborns, demonstrated that supplementation with EPA and DHA prolonged pregnancy by 1.57 days (95%CI: 0,35 – 2.78 d, p=0.01), and increased head circumference by 0.26 cm (95%CI 0.02 – 0.49, p=0.03)(Szajewaska et al. 2006). In a Cochrane-analysis, fish oil prolonged pregnancy by 2.6 days (95 % CI 1.03- 4.07), and increased birth weight slightly (47 g, 95 % CI 1 g – 93 g). In a more recently published meta-analysis, birth weight of the child was 71g higher and pregnancy 4.5 days longer (Salvig & Lamont, 2011). This was also found in a recent intervention trial (Carlson et al, 2013).

Premature birth: According to a Cochrane-analysis of 6 randomized intervention trials with omega-3 fatty acids (2783 pregnancies), premature birth occurred less frequently in women supplementing EPA plus DHA (RR 0,69, CI 0.49-0.99), than in the control groups (Makrides et al, 2006). A more recent meta-analysis of intervention trials had a similar result: low risk for birth before week 37 of gestation (RR 0.61, 95%CI 0.40 – 0.93; p<0.05), and a substantially lower risk before week 34 (RR 0,34, 95%CI 0.09 – 0.95) (Salvig & Lamont, 2011).

Pre-eclampsia: High levels of EPA and DHA in erythrocytes and plasma correlate with a low risk for hypertension and pre-eclampsia in pregnancy, as found in most, but not all epidemiologic studies (Brenna et al 2009, Qiu et al, 2006).

Post-partum depression: Low levels or low intake of EPA and DHA are associated with depression in pregnancy and childbed (Borja-Hart et al, 2010). Of seven intervention trials aiming at prevention of post-partum depression, three were positive (Borja-Hart et al, 2010). The trials were small, however (Borja-Hart et al, 2010). Meta-analyses comprising epidemiologic studies and intervention trials saw no clear-cut effect (Wojcicki & Heyman, 2011; Parker et al, 2015). Nevertheless, an early start and a dose of 2 g / day was recommended for future trials (Wojcicki & Heyman, 2011). The largest intervention trial ever conducted in pregnant women saw post-partum depression not reduced (Makrides et al, 2010). However, in more than 80% of participants levels overlapped between verum and placebo groups (Muhlhausler et al, 2014) – a typical phenomenon resulting from conventional trial design (discussed in more detail in the general part of this website). Recently, an intervention trial demonstrated a larger effect in verum than in placebo (Kaviani et al, 2014). Safety, tolerability and lack of alternatives make intervention trials with omega-3’s attractive in the future.

Complex brain function of the child

Many randomized controlled intervention trials investigated supplementing the diet of pregnant women with omega-3 fatty acids in doses from 0.13 – 3.3 g EPA plus DHA / day (mostly around 2 g / day) in comparison to placebo (Koletzko et al, 2007, Brenna et al, 2009, Carlson 2009, Innis 2008). Parameters representative for complex brain function, like visual acuity, attention spans, eye – hand coordination, problem solving behavior, and other were improved in children, whose mothers had verum supplements in pregnancy (Koletzko et al, 2007, Brenna et al, 2009, Carlson 2009, Innis 2008). The improved brain functions correlated with levels of EPA and DHA in the mother (if assessed). If pregnant women had higher levels of EPA plus DHA, the intelligence quotient of their children was higher at age seven (in comparison to mothers with lower levels, Brenna et al, 2009, Helland et al, 2008).

Other parameters found improved by supplementation with EPA and DHA in pregnancy were heart rate variability and sleep duration (Gustafson et al, 2013).
Allergies, colds and inflammatory diseases early in life
In a randomized trial, food allergies were less frequent in children of mothers having supplemented EPA plus DHA in pregnancy, in comparison to controls (Furuhjelm et al, 2009). Fewer and shorter colds were observed in children of mothers having supplemented EPA plus DHA in pregnancy, as compared to controls (Imhoff-Kunsch et al, 2011, Escamilla-Nuñez et al, 2011). Supplementing EPA plus DHA in pregnancy also reduced respiratory allergies and atopic eczema in the children (Palmer et al, 2012). Reduced tendency towards allergies and a less severe course of respiratory infections further support the supplementation with EPA plus DHA in pregnancy. We suggest to target the supplementation towards a HS-Omega-3 Index between 8 and 11%.


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