pears to be a greater transplacental gradient in proportions of AA and DHA at term than midterm. Such a difference is consistent with the decline in plasma concentration of DHA between the beginning and end of pregnancy and suggests that the placenta is progressively depleting maternal DHA as the fetus grows (Crawford, 2000). Although the mechanism of transport for AA and DHA has not been elucidated, Campbell et al. (1998) proposed and Larque et al. (2003) identified a fatty acid binding protein, p-FABPpm, in placental tissue that showed a higher binding capacity for DHA and AA than linoleic acid (LA) and oleic acid (OA).
Because lower visual acuity was observed in rhesus monkeys with lower brain DHA (p<0.001) (Neuringer et al., 1984), this outcome has been the most studied in human infants relative to DHA intake. The first experimental studies that provided DHA, AA, and EPA to preterm infants demonstrated an increase in blood lipid content of these fatty acids as well as increases in visual acuity (Uauy et al., 1990; Carlson et al., 1993). Subsequently, DHA in cord blood and infant blood lipids has been used as an indicator of DHA exposure of the fetus or infant.
DHA status in infants is determined using blood as a biomarker because levels of DHA in the brain correlate with those in erythrocytes (Makrides et al., 1994). Previous studies have identified a correlation between dietary intake of AA, DHA, and other LCPUFAs; their respective levels in blood and erythrocyte phospholipids; and performance on tests of visual acuity and sensory-motor development in preterm infants (Uauy et al., 1990; Bjerve et al., 1993; Carlson et al., 1993). Observational studies that associate higher maternal EPA or DHA intake with higher stereoacuity or visual acuity in their infants are discussed below. Subsequently, maternal EPA/DHA supplementation or biochemical markers for their intake have been assessed as indicators of an association between increased intake levels of EPA/DHA and improved sensory-motor development in infants and young children.
Williams et al. (2001) observed that stereoacuity at 3.5 years of age in a subset of 435 healthy full-term children from the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort was associated with breastfeeding, greater maternal age, and maternal antenatal consumption of fatty fish. After multiple logistic regression, only breastfeeding and maternal consumption of fatty fish at least once every 2 weeks remained significant predictors of higher stereoacuity (foveal acuity) in the children. Among 4733 women in the main ALSPAC cohort for whom both dietary intake and red blood cell DHA percentage were available, only intake of fatty fish was associated with higher red blood cell DHA levels, an indicator of higher maternal DHA status. Higher maternal DHA intake is also known to