Essential fatty acids (EFA) are vitally important structural elements of cell membranes and, therefore, instrumental in the formation of new tissues. The primary EFA cannot be synthesized by man and, consequently, humans depend on dietary sources for an adequate EFA supply. Fetal development is associated with a high EFA requirement, and for its EFA supply, the developing fetus depends on the availability of maternal EFA. At delivery, a strong correlation is observed between the relative amounts of the various EFA in maternal and umbilical plasma phospholipids (PL), which underlines this fetal dependence. In a longitudinal study, we observed that, in women, the EFA status progressively decreases during pregnancy. This particularly holds for cervonic acid (CA, 22:6n-3, also named Docosahexaenoic acid, DHA), the major structural and functional EFA in the CNS. In addition, evidence was obtained for CA mobilization from maternal stores during pregnancy. Furthermore, the maternal CA status appeared significantly higher in primigravida than in multigravida. This was associated with a tendency for the first child of a given woman to have a higher CA status than her following children. This suggests that maternal CA mobilization during pregnancy occurs from a pool that is not easily replenished after pregnancy. The fetal CA status of premature infants is positively related to head circumference, birth weight and birth length. This may imply that increasing the fetal CA status could promote fetal growth and, thereby, improve the general prognosis of prematures. In conclusion, our data suggest that increasing the maternal EFA intake during pregnancy may be beneficial to both mother and child.(ABSTRACT TRUNCATED AT 250 WORDS)