Can dilutional anemia occur in the third trimester of pregnancy?

From the Guidelines

Dilutional anemia can indeed occur in the third trimester of pregnancy due to the significant increase in blood volume and relatively lower increase in red blood cell production. This condition is a result of the physiological changes that occur during pregnancy, where blood volume increases by about 50%, while red blood cell production increases by only about 20-30% 1. The disproportionate increase in blood volume leads to a relative dilution of red blood cells in the larger plasma volume, causing hemoglobin and hematocrit levels to appear lower than pre-pregnancy values.

Some key points to consider in the context of dilutional anemia in the third trimester include:

• Normal hemoglobin levels during the third trimester may be as low as 10.5-11 g/dL, compared to non-pregnant values of 12-16 g/dL.
• This physiologic anemia is generally not harmful and doesn't require treatment unless hemoglobin falls below 10.5 g/dL, which might suggest true anemia requiring iron supplementation.
• Regular prenatal care includes monitoring hemoglobin levels to distinguish between normal dilutional anemia and true anemia that requires intervention, as noted in the context of screening for iron deficiency anemia 1.
• The body makes these adaptations to accommodate increased blood flow to the uterus and to protect against blood loss during delivery, highlighting the importance of understanding the physiological basis of dilutional anemia in pregnancy.

It's crucial to differentiate between dilutional anemia, which is a physiological adaptation, and true anemia, which may require intervention such as iron supplementation, especially considering the current recommendations and evidence on screening for iron deficiency anemia during pregnancy 1.

From the Research

Dilutional Anemia in Third Trimester

• Dilutional anemia, also known as physiologic anemia, occurs in pregnancy due to an increase in plasma volume that exceeds the increase in red cell mass 2.
• This condition is most pronounced in the third trimester, where the plasma volume has increased significantly, leading to a dilutional effect on the red blood cells 3.
• Studies have shown that daily iron supplementation with or without folic acid can increase hemoglobin levels in the third trimester and reduce the risk of anemia 3.
• However, intermittent iron supplementation may not have the same effect, and its use in the third trimester is still being researched 4.
• It is essential to note that anemia in pregnancy can have adverse effects on both the mother and the fetus, and prompt diagnosis and treatment are crucial 5.

Causes and Treatment of Anemia in Pregnancy

• Anemia in pregnancy can be caused by iron deficiency, acute blood loss, or other factors 5.
• Iron deficiency anemia is the most common type of anemia in pregnancy, accounting for 75% of all anemias 2.
• Treatment options for anemia in pregnancy include oral iron supplementation, parenteral iron, and erythropoietin 2, 6.
• The choice of treatment depends on the severity of the anemia, the presence of other medical conditions, and the gestational age of the pregnancy 6.

Importance of Screening and Diagnosis

• Screening for anemia is essential in pregnancy, as it can help identify women at risk of adverse outcomes 5.
• Early diagnosis and treatment of anemia can improve maternal and fetal outcomes, reducing the risk of complications during pregnancy and childbirth 5, 3.
• Healthcare providers should be aware of the risks and benefits of different treatment options and make informed decisions based on the individual needs of each patient 4, 6.