Correlation between blood parameters in the early and later stages of pregnancy: A retrospective study

Objective: Anemia is common in pregnant women and is associated with various maternal and fetal complications. However, the effect of fluctuations in hemoglobin levels during pregnancy on birth outcomes remains unclear. Therefore, we investigated the association between maternal hemoglobin levels at different stages of pregnancy and delivery outcomes. Methods: This retrospective study included 215 women who gave birth between 2018 and 2023. Hemoglobin levels were measured at three time points during pregnancy: first trimester (approximately 12 weeks), second trimester (13–27 weeks), and third trimester (28–36 weeks). The primary outcomes were the associations between hemoglobin levels and birth weight, birth weight Z-score, placental ratio, and placental weight. Statistical analyses were conducted to control for maternal and fetal factors and to determine the correlations between hemoglobin levels and delivery outcomes. Results: Hemoglobin levels in the first trimester were the best predictors of anemia in the third trimester (area under the curve (AUC), 0.63; sensitivity, 65 %; specificity, 65 %). Hemoglobin levels were inversely associated with birth weight, birth weight Z-score, placental ratio, and placental weight. The overall accuracy of predicting iron-deficiency anemia was high (sensitivity, 71 %; specificity, 76 %; AUC, 0.76). Significant associations were observed at p < 0.001. Conclusions: Fluctuations in hemoglobin levels during pregnancy were significantly associated with adverse birth outcomes. Monitoring and managing hemoglobin levels early in pregnancy can improve maternal and fetal health by reducing the risk of low birth weight and other complications. Further research is needed to explore the mechanisms underlying these associations and develop targeted interventions.