A Longitudinal Study of Iron Intake and Iron Status in Pregnant Women

Abstract

Objective: This study aimed to investigate the cross-sectional and longitudinal iron intake and iron status during pregnancy, considering the validity of dietary reference intakes for iron in Japanese pregnant women.
Methods: We assessed the iron intake and iron status in 103 Japanese women recruited at 5~12 weeks of pregnancy. Data were collected during the first, second, and last trimester, at delivery and the first postpartum month. These date included anthropometric and obstetric measurements, with or without administration of iron, dietary intakes, and blood samples.
Results: The iron intake was found to be below the recommended dietary allowance in 71.8% of subjects in their first trimester and in 98.1% of those in their second trimester. Maternal red blood cell count, hemoglobin concentration, hematocrit level, and serum iron concentration significantly decreased during the second and last trimester compared to those during the first trimester. However, these levels normalized in the first postpartum month to those during the first trimester. Prevalence of maternal anemia (hemoglobin, <11 g/dl; hematocrit, <33%) was 4.9%, 41.7%, and 53.4% in the first, second, and last trimester, respectively. However, MCV and MCH were within the criteria (MCV, 79.0~100.0 fl; MCH, 26.3~34.3 pg). Low-birth-weight and preterm baby were observed in only 3 and 1 case, respectively.
Conclusions: In this study, iron intake was found to be inadequate; however, we believe that an increase in iron absorption caused the increase in demand for iron. Restricting excessive iron intake, such as the dietary reference intake, maintained the iron levels in most subjects.