LAUSR

Nutritionally related anemia during pregnancy can have serious consequences for the mother and child, including poor birth outcomes and neurodevelopmental consequences. Few published studies have evaluated the reference intervals of analytes such as ferritin, total iron binding capacity (TIBC), transferrin saturation (TS), folate, and vitamin B12 during pregnancy. Identification of anemia due to iron, folate, and B12 deficiencies may allow appropriate treatment and improved outcomes for both mother and child. We performed a retrospective analysis of data collected from a network of national independent laboratories and isolated a pregnant population for which the week of pregnancy and test results for ferritin, TIBC, TS, red cell indices, folate, and vitamin B12 were available. Test results were only included for analysis if hemoglobin (Hb) was greater than 11 g/dL. All analytes were further stratified by trimester and analyzed by multimodal decomposition method using R. A minimum of 2,691, 2,996, 7,952, 7,484, 7,510, and 3,906 patient results were utilized for analysis of folate, ferritin, iron, TIBC, TS, and vitamin B12, respectively. Verification of the derived reference intervals was performed using an in-house employee wellness screening database that included test results from female employees who had normal C-reactive protein (CRP), Hb greater than 11 g/dL, and the weeks of pregnancy, with successful birth, and without any relevant medical or pharmacy claims. These trimester specific reference intervals were compared to in-house previously derived reference intervals for women of childbearing age. Although comparison with women of childbearing age showed similar reference interval values for iron, vitamin B12, and folate with mild decreases both in the second and third trimesters, there were marked differences when comparing ferritin, TIBC, and TS reference intervals. Ferritin reference intervals particularly were much lower during pregnancy especially in the second and third trimesters compared to women of childbearing age. Determination of trimester-specific reference intervals is possible for several key analytes for evaluation of anemia using a large database collected from a national network of independent laboratories given the ability to verify with a well-defined wellness employee dataset. Use of such reference intervals may be helpful in identifying causes of anemia during pregnancy, particularly iron deficiency, and enabling tailored use of these tests during pregnancy.