Anaemia of Pregnancy
During pregnancy, your body works harder than ever to support both you and your growing baby. One common challenge many pregnant women face is anaemia—when your blood doesn’t have enough red blood cells to carry oxygen throughout your body. While mild anaemia is a normal part of pregnancy, understanding this condition and managing it properly is essential for your health and your baby’s development.
Table of contents
- What is Anaemia During Pregnancy?
- Causes and Types of Anaemia in Pregnancy
- Who is Most at Risk?
- Signs and Symptoms
- How Anaemia Affects You and Your Baby
- Testing and Diagnosis
- Treatment Options
- Prevention Through Diet and Lifestyle
What is Anaemia During Pregnancy?
Anaemia is a condition where your blood doesn’t have enough red blood cells to carry oxygen throughout your body[1]. Red blood cells contain an important protein called hemoglobin, which holds oxygen and helps transport it from your lungs to your body’s tissues and to your baby[1]. When your body doesn’t get enough oxygen from your blood, it can’t function properly[1].
During pregnancy, your body goes through significant changes. The amount of blood in your body increases by about 20% to 30%, which increases the supply of iron and vitamins that the body needs to make hemoglobin[2]. This increase means your body needs more iron to produce more red blood cells[1]. However, a disproportionate increase in plasma volume—by 40 to 50%—results in a condition called hemodilution, or the dilution of blood[14].
Because of these changes, mild anaemia is normal during pregnancy due to the increase in blood volume[2]. It’s common for women to become anaemic during pregnancy because they don’t have enough iron and other vitamins[1]. Globally, it is estimated that 37% of pregnant women are affected by anaemia[8].
Causes and Types of Anaemia in Pregnancy
Pregnancy itself is a cause of anaemia because of the increase in blood volume[1]. To produce red blood cells and hemoglobin, your body needs a consistent supply of iron and vitamins. Without that supply, your body won’t produce enough hemoglobin to properly carry oxygen to your organs[1].
There are more than 400 types of anaemia, but some are more common during pregnancy[1]:
Iron-deficiency anaemia is the most common type during pregnancy[4]. This occurs when the body doesn’t have enough iron to produce adequate amounts of hemoglobin[4]. During pregnancy, your baby uses your red blood cells for growth and development, especially in the last three months of pregnancy[3]. If you’re not getting enough iron or certain other nutrients, your body might not be able to produce the amount of red blood cells it needs to make the additional blood required during pregnancy[4].
Folate-deficiency anaemia develops when you don’t get enough folate, a B vitamin found naturally in certain foods like green leafy vegetables[4]. The body needs folate to produce new cells, including healthy red blood cells[4]. During pregnancy, women need extra folate, but sometimes they don’t get enough from their diet[4]. Folate deficiency can directly contribute to certain types of birth defects, such as neural tube abnormalities like spina bifida and low birth weight[4].
Vitamin B12 deficiency anaemia occurs when you don’t get enough vitamin B12 from your diet[1]. Vitamin B12 is important in making red blood cells and protein[3]. Women who don’t eat meat, poultry, dairy products, and eggs have a greater risk of developing vitamin B12 deficiency[4]. Strict vegetarians or vegans are at greater risk of having a vitamin B12 deficiency[3].
Other common causes of anaemia can also contribute to anaemia during pregnancy, including certain diseases like sickle cell anaemia and thalassemia, heavy menstrual flow before pregnancy, and ulcers and polyps[1]. Blood loss during and after delivery can also cause anaemia[4].
Who is Most at Risk?
All pregnant women are at risk for becoming anaemic because they need more iron and folic acid than usual[4]. Throughout pregnancy, the amount of blood in your body increases by 20% to 30%, which means your body needs more iron to produce more red blood cells[1].
However, certain factors put you at higher risk for developing anaemia during pregnancy. You are at greater risk if you are pregnant with multiples, such as twins or more[2]. Having two pregnancies close together increases your risk because your body hasn’t had time to restore its iron stores[2].
If you are vomiting frequently due to morning sickness, you may be at higher risk[1]. Women who are not consuming enough iron-rich foods in their diet are more likely to develop anaemia[2]. If you experienced a heavy menstrual flow before pregnancy, you may have started pregnancy with lower iron stores[1].
Pregnant teenagers face a higher risk of anaemia[4]. Women who had anaemia before becoming pregnant are also at increased risk[4]. Additionally, women who are strict vegetarians or vegans are at greater risk of vitamin B12 deficiency[3], and those with celiac disease or Crohn’s disease, or who have had weight loss surgery where the stomach or part of the stomach has been removed, face higher risk[3].
Signs and Symptoms
You may not notice any symptoms of mild anaemia at first[1]. Many of the symptoms of anaemia during pregnancy are also symptoms you may experience even if you are not anaemic[2]. In the early stages of anaemia, you may not have obvious symptoms[4].
Over time, as anaemia develops, you may feel tired, cold, and experience shortness of breath[1]. Fatigue and weakness are among the most common symptoms[2]. You might notice progressive paleness of your skin, especially on your skin, lips, nails, palms of hands, or the underside of your eyelids[3].
Other symptoms include dizziness or feeling lightheaded[1]. You may experience a fast or irregular heartbeat[4]. Some women report headaches[1]. Your skin may appear pale, dry, or bruise easily[1]. You might have a sore tongue[1].
Some women experience trouble concentrating[2]. An unusual symptom is restless legs syndrome—unintended movement in the lower leg—or cravings for nonfood items such as dirt, ashes, clay, or chalk, which can be a sign that you don’t have enough iron in your blood[1].
How Anaemia Affects You and Your Baby
Severe anaemia is not typical during pregnancy, but both mild and severe anaemia require treatment to protect the health of you and the fetus[1]. Anaemia can leave you feeling tired and weak, and if it is severe but goes untreated, it can increase your risk of serious complications[4].
The developing fetus relies on you to get enough iron, vitamin B12, and folic acid[1]. Anaemia can affect the growth of the fetus, especially during the first trimester[1]. If you are significantly anaemic during your first two trimesters, you are at greater risk for having a preterm delivery or a low birth weight baby[2].
Severe iron deficiency anaemia during pregnancy raises the risk of premature birth—when a baby is born before 37 complete weeks of pregnancy[5]. Iron deficiency anaemia during pregnancy is also linked to having a low birth weight baby[5]. Some studies show a higher risk of infant death immediately before or after birth in pregnant people who have severe iron deficiency anaemia[5].
If anaemia goes untreated, your baby is at higher risk of having anaemia after birth, which can lead to developmental problems[1]. More severe anaemia can put your baby at a greater risk for anaemia later in infancy[2]. Being anaemic also burdens the mother by increasing the risk of blood loss during labor and making it more difficult to fight infections[2].
Anaemia during pregnancy doesn’t directly cause miscarriage, but severe anaemia can cause pregnancy complications[1].
Testing and Diagnosis
A blood test called a complete blood count (CBC) can diagnose anaemia[1]. This blood test is often done at one of your first prenatal appointments[1]. Doctors typically screen for iron deficiency anaemia with a complete blood count in the first trimester and often in the later second trimester to optimize for delivery[2].
The test measures your hemoglobin level and counts your red blood cells[2]. During pregnancy, certain hemoglobin levels are classified as anemic. In the first trimester, hemoglobin below 11 g/dL indicates anaemia. In the second trimester, the threshold is hemoglobin below 10.5 g/dL. In the third trimester, hemoglobin below 11 g/dL again indicates anaemia[14].
Iron levels can change during pregnancy, so your healthcare provider may test your blood again in the second and third trimesters[24]. If the initial tests show anaemia, additional iron studies or other evaluations may be needed[2]. Measurement of serum ferritin has the highest sensitivity and specificity for diagnosis of iron deficiency anaemia unless there is a concurrent inflammatory condition[17].
If you have anaemia, your healthcare provider may order more tests or refer you to a specialist, such as a hematologist—a doctor who specializes in blood conditions[2].
Treatment Options
In most cases of anaemia during pregnancy, tweaks to your diet can put you on the right path[1]. Each type of anaemia is treated differently, but the main approaches include eating foods rich in iron and taking supplements[9].
Oral iron therapy is given as the first-line treatment for iron deficiency anaemia[17]. There usually is enough iron in your prenatal vitamin to prevent anaemia, but your provider may prescribe an extra iron pill if you are anaemic[20]. For many people, prenatal vitamins have enough iron to support extra blood volume[24].
If you need more iron, your healthcare provider may prescribe a separate iron supplement[24]. Make sure you get at least 27 mg of iron each day[2]. Your obstetrician will also prescribe vitamins to ensure that you have enough iron and folic acid[2].
If the iron tablet upsets your stomach, take it with a small amount of food[20]. Do not take your iron tablet with dairy products or calcium supplements, as these can interfere with iron absorption[20]. Taking iron supplements can cause side effects such as black, green, or dark stool, constipation, diarrhea, heartburn, nausea, stomach cramps, or worsened morning sickness[24]. If you have side effects, your healthcare provider can suggest a different dose or kind of iron supplement[24].
Intravenous (IV) iron therapy is an alternative therapeutic option in patients who do not respond to oral iron therapy, have adverse reactions, do not comply with oral iron treatment, have a very low hemoglobin concentration, and require rapid iron repletion[17]. A recent large study involving 4,368 participants in India found that a single dose of iron delivered intravenously early in the second trimester is a safe and effective intervention for anaemia during pregnancy[12]. Those who received IV iron had significantly lower rates of needing additional non-study IV iron or a blood transfusion prior to delivery[12].
If you do become anemic during your pregnancy, it can usually be treated by taking additional iron supplements[2]. Ask your doctor about your risk for anaemia, and make sure you are tested at your first prenatal visit. You also may want to get tested 4 to 6 weeks after delivery[2].
Prevention Through Diet and Lifestyle
Good nutrition is the best way to prevent anaemia if you are pregnant or trying to become pregnant[2]. Eating foods high in iron content can help ensure that you maintain the supply of iron your body needs to function properly[2].
Foods rich in iron include dark green leafy vegetables, red meat, fortified cereals, eggs, and peanuts[2]. The form of iron in meat products, called heme, is more easily absorbed than the iron in vegetables[20]. If you are anaemic and you ordinarily eat meat, increasing the amount of meat you consume is the easiest way to increase the iron your body receives[20].
Other iron-rich foods include chicken, lean beef, veal, pork, or lamb, fish, dried beans, lentils, kidney beans, lima beans, navy beans, spinach, beets, sauerkraut, tofu, oatmeal, raisins, and dried apricots[20]. Cooking with cast iron pots can add up to 80 percent more iron to your food[20].
Eat foods high in folic acid, such as dried beans, dark green leafy vegetables, wheat germ, and orange juice[20]. All kinds of liver (except fish) are good sources of iron, however, liver should not be eaten more than once a week[20].
Eating foods high in vitamin C, such as citrus fruits and fresh, raw vegetables, can help you absorb iron better[20]. Vitamin C strengthens your immune system and helps you absorb iron better[24].
Limit foods that interfere with iron absorption, such as added sugars and natural or artificial sweeteners, coffee and black tea, and milk and dairy products[24]. Eat calcium-rich foods at different times than you eat iron-rich foods or supplements[24]. Also limit processed meats[24].
Continue taking your prenatal multivitamin and mineral pill which contains extra folate[20]. Good nutrition before getting pregnant is important to help build up your iron stores[3].
