Folate economy in pregnancy.

Pregnant women are prone to becoming folate deficient because there is a significant increase in folate requirement during pregnancy and folate intakes of pregnant women are often insufficient. Reduced folate levels in blood and neutrophilic hypersegmentation reflect a negative folate balance. Possible consequences of a low maternal folate status may be pregnancy complications such as abortion, abortus imminens, abruptio placentae, and congenital malformations. The role of folic acid in the etiology of neural tube defects has been discussed for decades. The importance of an adequate maternal folate status in the prevention of neural tube defects has been demonstrated by observational and controlled intervention trials. However, the mechanism of the protective effect of periconceptional folate supplementation is not completely understood. Metabolic disorders are probably involved in the pathogenesis of neural tube defects so that a relative folate shortage rather than folate deficiency seems to be responsible for the disturbed neural tube development, which can be compensated for by a higher folate intake.