Anemia in Pregnancy: Causes, Risks, Treatment, and Prevention

During pregnancy, the health of your growing baby depends on your own health. While this is an honor, it’s also a major demand on your body, requiring changes to nearly every body system. Cardiovascular physiology is drastically changed during pregnancy, and these changes can contribute to anemia in pregnancy.¹ Knowing the causes, risks, treatment options, and prevention strategies for pregnancy anemia can keep you on the lookout and help maintain health for both mom and baby.

Anemia is defined as the decreased ability of the blood to carry oxygen.¹ This is due to a low number of red blood cells, low hemoglobin levels within the red blood cells, or low concentration of red blood cells within the blood plasma.² Hemoglobin is the protein within your red blood cells that binds oxygen and delivers it to cells throughout the body.³ When hemoglobin drops below 10-11 grams per deciliter, depending on the trimester, anemia in pregnancy may be diagnosed.^1,2

Pregnancy puts increased demands on a mother’s body and her blood, which makes her more susceptible to anemia. There are two main causes of anemia in pregnancy:^1,11

Blood volume rises during pregnancy, but plasma volume increases more than the red blood cells. Plasma volume rises by nearly 50%, but red blood cells rise by only about 18%. Because of this, the concentration of hemoglobin in the blood decreases by dilution, giving you a low relative red blood cell count in pregnancy.^1,11 Hematocrit is the concentration of red blood cells compared to total blood volume, so it’s normal to have somewhat low hematocrit in pregnancy.^3,11 This is called physiologic anemia, which can be considered normal and is thought to be potentially beneficial during pregnancy. Slightly thinner blood due to a smaller concentration of red blood cells may make it easier for blood to flow freely to the uterus and placenta.^1,11

After dilution, low iron in pregnancy is the main cause of pregnancy anemia.² During pregnancy, there’s an increased demand for nutrients, particularly iron, folic acid, and vitamin B12.^1,2 In addition to needing more of these nutrients than usual during pregnancy, many women don’t consume enough, don’t absorb what they’re consuming, and are losing more nutrients than usual, hence the recommendation for folate and iron supplementation for pregnant women.¹

Types of Anemia That Affect Pregnant and Postpartum Women

Pregnant women can be affected by many types of anemia. However, the most common are iron deficiency anemia and folate deficiency megaloblastic anemia:^1,11

Iron deficiency is the cause of 75% of diagnosed cases of anemia during pregnancy.¹ Iron is a building block of hemoglobin, the part of the red blood cell that delivers oxygen and removes carbon dioxide. During pregnancy, there’s an increase in the production of red blood cells in order to increase blood volume. If the increased iron requirement isn’t met through diet and supplementation, a pregnant woman may develop iron deficiency and subsequent anemia.⁴

Acute blood loss after birth is a leading cause of anemia in pregnancy and the peripartum period. This is due to significant blood loss that depletes the body’s iron stores and red blood cells. Postpartum hemorrhage, defined as blood loss greater than 1,000 milliliters within the first 24 hours post-birth, is a major contributor to this condition. It’s often accompanied by signs and symptoms of hypovolemia, such as low blood pressure, rapid pulse, and dizziness, which further complicates the recovery process for new mothers. Effective management and timely intervention are crucial to prevent severe anemia and ensure maternal health.^11,12

During pregnancy, your baby takes much of your supply of folic acid, and you also absorb it more slowly. Folic acid is a B vitamin that helps produce red blood cells. Without sufficient folate, your body can make too few red blood cells that are very large, oval-shaped, and short-lived. This renders them less efficient at carrying oxygen throughout your body.⁵

Signs and Symptoms

When your organs aren’t receiving enough oxygen due to anemia in pregnancy, you can suffer symptoms such as:^1,2

• Headache
• Extreme tiredness
• Fast breathing and heart rate
• Paleness
• Craving of ice or dirt/clay during pregnancy
• Uncomfortable breathing
• Lightheadedness
• Exercise intolerance
• Depression and anxiety
• Brain fog and poor work performance

When I had anemia, I experienced every single one of these symptoms. It’s easy to write them off as normal parts of pregnancy. But if you’re feeling any of the above, your doctor can order a simple blood test to assess for anemia. A complete blood count is standard in the first trimester and again between 24 and 28 weeks of gestation, but you can always request another.²

Pregnancy places increased demands on your body and can take a toll. This is why a nutrient-dense diet is especially important. If these demands are especially high, or you aren’t meeting them with intake, you may be at a higher risk of developing anemia in pregnancy:^1,6

• Inadequate diet
• Lack of supplementation
• Pregnancy with multiples
• A small gap between pregnancies
• Teen pregnancy
• Frequent vomiting due to morning sickness
• History of anemia or heavy periods

Hemoglobin is built with iron. If you’re wondering how to raise hemoglobin, your body needs to have an adequate supply of iron. Many doctors recommend that all pregnant women take a prenatal vitamin with iron. If you’re iron deficient, you may need a separate iron supplement in pregnancy:⁶

The CDC recommends that all pregnant women begin iron supplementation at the first prenatal visit.¹³ A pregnant woman with iron deficiency anemia should take a 30-60 milligram dose of iron, three to four times per day, for a total of 200-300 milligrams per day.¹ As for what helps iron absorption, vitamin C increases the absorption of dietary and supplemental iron, and calcium impedes iron absorption. Therefore, consider taking your iron supplement with orange, tomato, or strawberry and avoid dairy or calcium-fortified orange juice at the same time.⁶

Iron supplements can cause gastrointestinal side effects such as nausea, vomiting, diarrhea, and constipation. Slow-release iron capsules or liquid iron may decrease these side effects and make iron supplementation easier for a pregnant woman to stick to.¹

When an oral iron supplement isn’t tolerated or ineffective, your doctor may consider an iron infusion in pregnancy. Iron infusions can deliver iron directly to the blood more quickly than dietary supplementation; however, it still takes your body the same amount of time to make the red blood cells from the iron. While iron infusions bypass the gastrointestinal side effects of oral supplementation, there are risks of reaction to the infusion, from allergic reaction to fever and skin staining.¹

Yes, iron deficiency anemia is associated with low birth weight, preterm delivery, and perinatal mortality.¹¹ Maternal iron deficiency in pregnancy is also associated with behavioral and brain development issues in children.² Besides the risks of anemia on the baby, it also has consequences for the mother. Anemia in pregnancy can increase the likelihood of C-section birth, postpartum anemia, needing a blood transfusion at delivery, and even postpartum depression.^2,6

Sometimes, anemia is unavoidable due to normal blood changes during pregnancy or physiologic anemia.¹ However, good nutrition is the best way to prevent severe anemia in pregnancy. Make sure you’re consuming enough dietary iron and supplementing if necessary.⁶

Dietary iron is most readily available to the body through animal protein sources, which provide heme iron.⁷ These include lean red meat, poultry, and fish.⁶

Plant sources of iron are called non-heme. Non-heme iron is less easily absorbed but isn’t linked to colorectal cancer in the same way that heme iron is.⁷ As for what vegetables are high in iron, aim for dark, leafy green vegetables, dried beans and peas, and nuts and seeds.^6,8 Finally, many breads and breakfast cereals are fortified with non-heme iron.⁶

While no singular food is going to cause or prevent anemia in pregnancy, there are some foods to be mindful of to optimize your absorption of dietary iron:⁸

Although dairy is an excellent protein source and a good choice during pregnancy, you shouldn’t consume dairy at the same time as iron. Dairy contains a high amount of calcium, which impedes iron absorption. So, it’s best to space out eating dairy and iron by at least one hour.⁸

Found in coffee, tea, beer, and red wine, tannins can make it more difficult for the body to absorb iron.⁸ While you don’t have to eliminate these substances from your diet (though you likely aren’t drinking much beer and wine while pregnant anyway!), it can be helpful to space out your consumption of iron-rich foods or iron supplements from tannins.⁹

Phytic acid is present in grains, beans, nuts, and seeds. This antinutrient binds to minerals such as iron to make them unavailable to the body. To significantly reduce phytic acid content, you can soak your grains (such as rice or oats) in water overnight before draining, rinsing, and cooking them.¹⁰

Managing pregnancy anemia requires attention and proactive steps toward the health of mom and baby. Expectant mothers can prevent and treat anemia by consuming adequate dietary iron and supplementing as necessary, addressing underlying causes, and optimizing nutrient absorption. Anemia symptom awareness and testing can facilitate diagnosis and treatment, so never be afraid to request a blood test if you feel off. With proper attention and care, you can minimize anemia in pregnancy and promote a healthy pregnancy and baby.