From the Research
Fetal Growth Restriction and Hemoglobin Levels
- Fetal growth restriction (FGR) is a condition where a fetus does not grow at a normal rate inside the womb 1.
- Research suggests that both low and high hemoglobin (Hb) levels can be associated with FGR:
- Low Hb levels: A study found that pregnancies with hemoglobin H (HbH) disease, which is characterized by low Hb levels, were significantly associated with increased risks of FGR, preterm birth, and low birth weight 2.
- High Hb levels: Another study found that increased Hb at 27-29 weeks gestation is associated with reduced birthweight and an increased risk of admission to the Neonatal Unit and adverse fetal outcome 3.
- A retrospective cohort study found that anemia severity during pregnancy was associated with increased risks of FGR, with moderate or severe anemia associated with increased risks, while mild anemia was associated with decreased risks 4.
- A study investigating cell-free hemoglobin in the fetoplacental circulation found that elevated levels of free fetal hemoglobin (fHbF) contribute to increased fetoplacental vascular resistance and impaired endothelial protection, offering a novel insight into FGR 5.
Key Findings
- FGR is associated with both low and high Hb levels, depending on the severity of anemia and other factors 3, 2, 4.
- Anemia severity during pregnancy is associated with increased risks of FGR, with moderate or severe anemia associated with increased risks, while mild anemia is associated with decreased risks 4.
- Elevated levels of fHbF contribute to increased fetoplacental vascular resistance and impaired endothelial protection, which may contribute to FGR 5.