Iron deficiency is the most common cause of anemia in pregnancy. Pregnant women with anemia are, in general, exclusively treated with iron supplementation. We observed that several pregnant women with anemia who were nonresponsive to iron supplementation also had vitamin B6 deficiency, and that anemia in these cases improved with the administration of vitamin B6. Our prospective study in healthy pregnant women showed that blood levels of iron, ferritin and vitamin B6, in particular, fell to the lower limit of the nonpregnant reference range by the third trimester. We conclude that it is important to take into account the deficiency of vitamin B6 besides iron in the evaluation of anemia during pregnancy.
IntroductionAnemia during pregnancy can be caused by various factors including loss of blood; shortage of iron, folate or vitamin B12; or underlying diseases such as hemoglobinopathies (for example, thalassemia and sickle cell disease), chronic inflammatory diseases, autoimmune disorders and malignancies. The World Health Organization (WHO) recommends that the hemoglobin (Hb) level should be maintained at or above 110 g/l during pregnancy (WHO, 1992). Severe anemia may be associated with adverse effects on both the mother and the fetus. A study of a cohort of 629 pregnant women in Pakistan showed that the risk of preterm delivery and low birth weight was 4 and 1.9 times higher, respectively, in anemic women (Hb o110 g/l) than in pregnant women without anemia (Lone et al., 2004). Iron deficiency is the most common cause of nutritional anemia in pregnancy (WHO, 1992). As iron stores in the mother diminish during pregnancy due to the physiological increase in the red cell mass and additional demands of the fetus (Letsky, 2002), adequate dietary iron intake and iron supplementation must be ensured in pregnant women. Therefore, pregnant women with anemia are generally treated with iron supplementation. Despite the known possibility of decreasing levels of other micronutrients (including vitamin B6) during pregnancy and causing or aggravating anemia, such nutrient supplementation is not appreciably popular.This study indicates that vitamin B6 deficiency is one of the common causes of nutritional anemia in pregnancy. We conducted a prospective study of the variability of the serum levels of iron, ferritin, vitamin B6, vitamin B12, folate and total protein/albumin in healthy women during each trimester of pregnancy, and analyzed the clinical features of pregnant women with vitamin B6 deficiency.
Participants and methodsBetween December 2002 and February 2008, we performed an analysis of 56 pregnant women with anemia who had evidence of vitamin B6 deficiency at the National Center for Child Health and Development (NCCHD), Tokyo. To examine the cause of anemia, the serum concentrations of vitamin B6 (as the sum of pyridoxal-5 0 -phosphate (PLP) and pyridoxal) were measured in these subjects, using a highperformance liquid chromatographic method (Ubbink et al., 1985). We collected the following data from all subjects: hist...