Amniotic fluid B-12 and folate levels associated with neural tube defects

Amniotic fluid levels of B-12 and folate in neural tube defect (NTD) affect ed pregnancies were compared with the weekly group mean +/-SD changes in am niotic fluid B-12 and folate levels of 10 unaffected pregnancies each week between 15 and 20 weeks' gestation age. Comparison was by analysis of varia nce (ANOVA) and Pearson's correlation to B-12 and folate levels and to the NTD samples of corresponding gestation age. Amniotic fluid B-12 and folate decreased 67 and 62%, respectively, between 15 and 20 weeks' gestation in t he unaffected pregnancies, associated with an increase in amniotic fluid vo lume. The mean +/-SD B-12 and folate of the NTD affected pregnancies (308 /-156 pg/mL and 3.1 +/-1.6 ng/mL) were below the mean +/-SD B-12 and folate of the total population of unaffected pregnancies (453 +/-155 pg/mL and 3. 9 +/-1.2 ng/mL). The correlation between gestation age and amniotic fluid B -12 was -0.9914 (p less than or equal to.0001) and -0.9599 (p less than or equal to.002) for amniotic fluid folate. The B-12 levels of the affected pr egnancies were below the range of unaffected pregnancies in four of the nin e affected pregnancies, and folate levels in two of the nine affected pregn ancies.