Investigation of red cell size-distribution histograms related to folate, vitamin B12 and iron state in the course of pregnancy.

Effects of gradually reduced stores of iron, folate or vitamin B12 on the erythron were investigated in the course of pregnancy in 23 subjects. Significant decreases in serum concentrations of the compounds above were shown at 20 weeks of gestation with a further decline later. An increased value for the microcyte fraction was established in two subjects, whereas seven other subjects showed increased values for the macrocyte fraction. As pregnancy proceeded a significant intra-individual change could be detected in the microcyte fraction in only one subject. In three of the seven above-mentioned subjects, the values measured for the macrocyte fraction demonstrated a further slight increase during the course of pregnancy. Values established for the absolute distribution width at half peak height (ADW0.5) did not reveal significant changes in the course of pregnancy. If compared with the mean cell volume (MCV) and ADW0.5 values, the microcyte and macrocyte fraction respectively may yield a sensitive and specific indication of anomalies of the erythron. Changes in successively determined haemocytometric values in several pregnant women might indicate decreased availability of nutrients for erythropoiesis. However, one may not draw definite conclusions because it is doubtful whether the condition of the stores in these circumstances will be reflected accurately by the corresponding serum concentrations.