Maternal first trimester iron status and its association with obstetric and perinatal outcomes

Purpose To assess the following in singleton pregnant women: (1) associations between first trimester iron deficiency and obstetric and perinatal outcomes, (2) overall first trimester iron status and (3) post-treatment iron status after intensified iron supplementation. Methods A prospective cohort study was conducted with linkage of first trimester hemoglobin and plasma ferritin with obstetric and perinatal data from a hospital database. Blood sample data were obtained from a Danish University Hospital. The cohort was divided into groups according to ferritin and hemoglobin: (1) iron-deficient anemic (ferritin < 30 ng/mL and Hb < 110 g/L), (2) iron-deficient non-anemic (ferritin < 30 ng/mL and Hb >= 110 g/L), and (3) iron-replete non-anemic (ferritin 30-200 ng/mL and Hb >= 110 g/L). Obstetric and perinatal outcomes in each iron-deficient group were compared to the iron-replete non-anemic group using multivariable logistic regression. The effect of 4 weeks intensified iron supplementation on hemoglobin and ferritin was assessed by groupwise comparisons. Results The cohort comprised 5763 singleton pregnant women, of which 14.2% had non-anemic iron deficiency, and 1.2% had iron-deficiency anemia. Compared to iron-replete non-anemic women, iron-deficient anemic women had a higher risk of gestational diabetes (aOR 3.8, 95% CI 1.4-9.0), and iron-deficient non-anemic women had a higher risk of stillbirth (aOR 4.0, 95% CI 1.0-14.3). In group 1 and 2, 81.5% and 67.7% remained iron-deficient after intensified iron supplementation. Conclusion Iron-deficiency anemia was associated with gestational diabetes, and non-anemic iron deficiency with stillbirth, although risk estimates were imprecise due to few events. Iron deficiency was present in 15.4% and often persisted despite 4 weeks intensified iron supplementation.

Automated summary

This study aimed to assess the associations between first trimester iron deficiency and obstetric and perinatal outcomes in singleton pregnant women, as well as overall first trimester iron status and post-treatment iron status after intensified iron supplementation. The results showed that iron-deficiency anemia was associated with an increased risk of gestational diabetes, while non-anemic iron deficiency was associated with an increased risk of stillbirth. However, the risk estimates were imprecise due to the small number of events. Additionally, iron deficiency was present in the first trimester in a considerable number of women and often persisted despite 4 weeks of intensified iron supplementation.