A number of research studies have demonstrated the positive effects of docosahexaenoic acid (DHA) supplementation during pregnancy on maternal and infant health (Koletzko 2008), including such benefits as a reduction in the risk of early preterm birth (Carlson 2013, Kar 2016), improved birth weight, and positive effects on aspects of immune function and allergy (Koletzko 2014). Randomized controlled trials (RCTs) investigating the effects of DHA supplementation during and after pregnancy on infant cognition have had mixed results (Colombo 2016). Differences in the measurement of cognitive function may in part account for the inconsistent results. Global standardized tests such as the Bayley Scales of Infant Development lack the sensitivity to detect the effects of DHA on specific cognitive domains. However, more targeted tests of attention based on constructs of information processing have been shown to correlate better with cognitive function later in childhood (Colombo 2012).
In this Phase III double-blind, placebo-controlled RCT, behavioral measures of visual attention were assessed at four, six, and nine months of age – periods of maximum developmental sensitivity. Those infants born to mothers prenatally supplemented with 600 mg DHA during the last half of pregnancy maintained higher levels of sustained attention and positive effects on behavioral state (fussiness) across the first year of life. The maintenance of sustained attention across the first year has previously been associated with higher preschool vocabulary at four years of age (Colombo 2009).
The primary dietary source of DHA is fatty fish. In many parts of the world, intakes of DHA are suboptimal during this critical period of time with many women failing to meet minimum recommendations of 200 mg DHA per day during pregnancy. Estimated dietary intake per capita for DHA in 47 developed and 128 developing countries demonstrate that 64% of these countries have a dietary DHA intake of less than 200 mg per day (Forsyth et al 2016).
Subjects from this Phase III RCT were recruited from term infants born to women who participated in the Kansas University DHA Outcomes Study (KUDOS). The KUDOS study was comprised of 230 subjects, with the intervention group given a daily dose of 600 mg DHA per day or an equivalent number of capsules containing half soy bean and half corn oil during the second half of pregnancy until delivery. The primary aim of the original study was to report the effect of prenatal DHA on gestation length and birth weight. The second goal was to determine the effects of prenatal DHA on the development of infants born to participating mothers. The current publication focuses on behavioral measures of visual attention and visual habituation and heart rate. Visual habituation is a well-known measure of non-associative visual learning measured during repeated presentations of stimuli on a screen with observers simultaneously coding infant looking and recording heart rate. Look duration reflects learning and memory, and declines over time (habituations); heart rate reflects the quality of attention during looking. A deceleration of heart rate during looking is associated with engagement and active processing. DHA supplementation did not affect some of the parameters such as heart rate, but infants of supplemented mothers maintained higher levels of sustained attention compared to the placebo group. The supplemented group also demonstrated significantly reduced attrition on tasks with less fussiness and crying at six and nine months of age.
The new study by Colombo et al. (1) demonstrates the positive effects of prenatal supplementation with DHA on sustained attention and behavioral state throughout the first year of life. This suggests an early programming effect resulting from DHA supplementation during pregnancy. These findings add to a growing body of evidence demonstrating the benefit of prenatal supplementation with DHA.