Anaemia in pregnancy: causes, symptoms, diagnosis and treatment
Published: 10 November, 2023 | 9'
Anaemia (from the Greek anaimia, meaning “deficiency of blood”) is defined by a decrease in the total amount of haemoglobin or the number of red blood cells. Anaemia is a common condition during pregnancy, affecting approximately 40% of pregnant women worldwide.
Causes of Anaemia in Pregnancy
Why does anaemia occur during pregnancy? Women during pregnancy experience an increase in plasma volume and red blood cell mass. However, the increase in volume is greater than the increase in red blood cell mass, resulting in a relative “decrease” in haemoglobin concentration, haematocrit, and red blood cell volume.
Anaemia is generally more common during the third trimester of pregnancy (up to one-third of women), with the most common causes being:
- Iron deficiency (microcytic anaemia): this type of anaemia develops when there is not enough iron in the body. Women need more iron during pregnancy (especially during the 3rd trimester) due to the increased mass of maternal red blood cells (approximately 35%), fetal development (red blood cell and muscle mass), and placental development. It is estimated that the total iron requirements during pregnancy are approximately 1-1.1 g and increase depending on the trimester of pregnancy: 1-1.2 mg/day in the first trimester, 4-4.7 mg/day in the second trimester, and over 5.6-6 mg/day in the third trimester.
- Folate and vitamin B12 deficiency (macrocytic anaemia): causes megaloblastic anaemia, a syndrome characterized by the presence of megaloblasts (immature red blood cells) due to asynchronous red blood cell (erythrocyte) maturation caused by DNA production abnormalities.
Other less common causes of anaemia during pregnancy
Two other rare causes of anaemia during pregnancy are:
- Hemoglobinopathies: inherited diseases caused by abnormalities in the production of hemoglobin in red blood cells. These diseases include thalassemia (alpha and beta), sickle cell anaemia, and variants of the globin chain. Since they have a hereditary component, a comprehensive examination of the pregnant woman and screening should be carried out to determine which member of the couple carries the gene for this disease. Hemoglobinopathies have significant implications for maternal health (e.g., worsening anaemia) and for the fetus (e.g., inheritance).
- Chronic anaemia: derived from infections such as malaria, hookworm infection, and tuberculosis, nutritional deficiencies such as vitamin A deficiency, or chronic or autoimmune kidney disease.
Symptoms and Complications of Anaemia in Pregnancy
Meeting nutritional needs during pregnancy, especially iron levels, is a priority. Evidence has shown that malnutrition before and during pregnancy and lactation can have severe short-term and long-term effects on both the mother and the child. Let’s look at the symptoms and consequences of untreated anaemia during pregnancy.
In general, in cases of mild anaemia, there may be no symptoms, or they may present nonspecific manifestations (e.g., tiredness or weakness).
The symptoms of anaemia can develop rapidly or slowly, depending on the cause of the anaemia, and can be detailed in the following table:
Lack of appetite
Shortness of breath or dyspnea
Jaundice or yellowish skin discoloration
Impaired mental performance
Anemic state changes
The complications that can occur due to the presence of anaemia affect the health of the pregnant woman, fetal development, and the health of the newborn. Let’s look at some of them.
- Obstetric complications: abortion, premature rupture of membranes, premature delivery, amniotic fluid volume lower than expected for gestational age (oligohydramnios), among others.
- Infections: pregnant women with anaemia are more susceptible to infections, especially urinary infections. Additionally, infection and spontaneous wound dehiscence are more frequent.
- Cardiovascular complications: hypertensive disorders and hemorrhagic incidents in the puerperium are more frequent when anaemia is present during pregnancy.
- Fetal development: iron deficiency doubles the risk of premature delivery and triples the risk of having a low birth weight baby. It also increases the chances of congenital defects. Specifically, folate deficiency can elevate the risk of neural tube defects.
Diagnosis and Treatment of Anaemia in Pregnancy
The World Health Organization (WHO) states that if haemoglobin (Hb) values are less than 11 g/dL and the haematocrit is less than 33% during pregnancy, the presence of anaemia is confirmed.
According to the haemoglobin levels, it is classified as:
- Mild anaemia (Hb 10 to 10.9 g/dl)
- Moderate anaemia (Hb 7 to 9.9 g/dl)
- Severe anaemia (Hb less than 7 g/dl)
The diagnosis of anaemia during pregnancy should be made by a healthcare professional and should include two phases:
- Clinical: it is recommended to perform a detailed medical history including diet/nutrition (vegan, vegetarian, and/or restricted eating patterns), factors that may affect dietary absorption (e.g., celiac disease), excessive iron/blood loss, as well as medical and family history, and history of previous pregnancies.
- Lab tests: a complete blood count is recommended, including mean corpuscular hemoglobin (MCH), and haematocrit, peripheral blood smear, serum folate and vitamin B12 levels, and measurement of serum iron concentration or serum ferritin concentration. The severity of anaemia is based on the individual’s haemoglobin/haematocrit level.
Treatment is adjusted depending on the type of anaemia identified, so:
- Microcytic Anaemia (Iron Deficiency): Recommendations from organizations such as the WHO, the Centers for Disease Control and Prevention (CDC), the European Food Safety Authority (EFSA), and other health organizations suggest iron intake based on local prevalence, iron intake through diet, and individualization of anaemia characteristics in pregnant women. Doses range from 16 to 120 mg/day.
- Macrocytic Anaemia (Folic Acid and Vitamin B12 Deficiency): The recommended folic acid intake ranges from 600 to 1000 micrograms per day, while the recommended intake for vitamin B12 is around 5 micrograms/day.
- Mixed Anaemia: This is a combination of the two types mentioned above, so nutrient intake should be adjusted according to the recommendations of a healthcare professional.
Tips for Preventing and Combating Anaemia During Pregnancy
During pregnancy, there are significant metabolic adjustments in nutrient utilization that promote fetal development. These adjustments require larger amounts of nutrients for the growth and metabolism of maternal and fetal tissues, as well as for storing nutrients in the fetus. The quality and quantity of the maternal diet affect fetal growth, as well as intestinal absorption, uterine and placental blood flow, cardiopulmonary function, placental transfer, and the proper utilization of nutrients and oxygen by the fetus.
Therefore, it is important to provide pregnant women with general recommendations, both dietary and hygienic, to ensure a successful pregnancy. According to the guidelines from the Ministry of Consumer Affairs and the Department of Health of the Community of Madrid, the following recommendations are advised:
- Wash hands with soap and hot water for at least 20 seconds before and after handling food, after contact with any dirty materials (diapers, waste, animals), and especially after using the bathroom.
- Hands, surfaces, and kitchen utensils should be thoroughly washed after handling raw meat, fish, poultry, unwashed fruits and vegetables, and any other raw foods.
- Store cooked foods in the refrigerator for the shortest possible time and keep them in closed containers, separate from cheeses and raw foods. If pre-cooked foods are purchased, respect the indicated expiration date.
- Wash raw fruits and vegetables.
- Cook meat thoroughly until it reaches a temperature of 71 ⁰C (the center of the product should change color).
- Carefully read the labels of food products, especially the warnings and directions for use.
- Limit consumption of caffeine from any source (coffee, tea, cola drinks, “energy” drinks, yerba mate, etc.).
Foods to Avoid
- Raw fish (such as sushi, sashimi, ceviche, carpaccios), refrigerated or marinated smoked fish, and raw oysters, clams, or mussels. In addition, large fish such as swordfish, shark, red tuna, or pike.
- Raw milk and fresh or soft cheeses (Brie, Camembert, Burgos cheese or Latin cheeses, mozzarella, and blue cheeses) if the label does not state that they are made with pasteurized milk. Industrial grated or sliced cheeses. Remove the rind from all cheeses.
- Raw eggs or preparations made with raw eggs (homemade sauces and mayonnaise, mousses, meringues, homemade cakes, tiramisu, homemade ice creams, eggnog, etc.).
- If there is no immunization against toxoplasmosis (consult a doctor), avoid consuming cured raw meat products (chorizo, salchichón, salami, cured ham, etc.).
- Consume only freshly squeezed juices or pasteurized packaged juices.
- Avoid alcoholic beverages.
- The energy needs during pregnancy range from 2200 to 2900 kcal/day.
- The daily diet should include 50% fruits and vegetables, ¼ cereals (preferably whole grains) and/or potatoes (not fried), ¼ protein-rich foods (eggs, fish, lean meats – portion size of 100 to 150 g, legumes, and unsalted raw or roasted nuts), dairy products (milk, unsweetened yogurts, kefir, cheeses, etc.); consume multiple servings of fruits (at least 3 servings per day), maintain constant hydration, and use vegetable oils containing unsaturated fats, such as olive oil.
- If following a vegetarian or vegan diet, special attention should be given to the intake of vitamin B12, calcium, and proteins. Increase consumption of nuts, calcium-rich foods such as dark leafy vegetables, and ensure an adequate combination of legumes and whole grains.
- The recommended daily nutrient intake is as follows:
- Proteins 1.1 g/kg
- Carbohydrates 175 g
- Fiber 14 g
- Omega 3 fatty acids (linoleic acid and α-linolenic acid) 15 g
Foods Rich in Iron
As mentioned, iron is one of the key nutrients for proper fetal development and the overall well-being of pregnant women. Foods that contain significant amounts of this mineral include2:
Supply >4 mg/day
3 ounces (85 g)
Grains and legumes
Dried sunflower seeds
Supply 2-4 mg/day
3 ounces (85 g)
3 ounces (85g)
Chocolate for Anaemia: Myth or Reality?
Cocoa beans (used to make chocolate) contain 9.3% water, 8.2% minerals, 18.81% protein, 13.85% fiber, and 46.1% carbohydrates. Drying the cocoa beans produces cocoa powder, which contains minerals such as 1544 mg of potassium, 734 mg of phosphorus, 499 mg of magnesium, 120 mg of calcium, and 13.9 mg of iron per 100 g, among others.
The processing of cocoa powder to make chocolate significantly reduces its mineral content, depending on the type. Dark chocolate is the best source of minerals and is recommended for consumption, containing 559-715 mg of potassium, 206-308 mg of phosphorus, 146-228 mg of magnesium, 56-73 mg of calcium, and 8-11.9 mg of iron per 45-85% cocoa solids, etc. However, it is important to note that while it provides significant iron content, it is a better source of magnesium and potassium, for example.
Chocolate can be an option in the diet, especially when consuming dark chocolate with 85% cocoa solids, but it is not recommended by medical societies or health organizations and is not mentioned in any official recommendations. Additionally, as chocolate is processed, the amount of fatty acids also increases, from 13.7 g/100 g in cocoa powder to 42.6 g in chocolate with 85% cocoa solids.
Iron and Vitamin Supplements
The goals of treating iron deficiency anaemia are to address the underlying cause, correct the anaemia, and replenish iron stores. To achieve this, it is essential to consume sufficient iron through the diet, which can be complemented with oral dietary supplements containing iron, as well as vitamins such as folate, vitamin B12, and vitamin C.
There are various forms of iron supplements available, each with different concentrations depending on the associated salt or other elements. One excellent alternative is iron bisglycinate3, which helps restore normal iron levels in the body. It provides a highly bioavailable and stable source of iron (due to its rapid intestinal absorption that respects the integrity of the intestine) and can be administered concurrently with other metals, reducing competition for absorption sites and chelation by other components present in the diet.
The iron requirements increase during pregnancy depending on the trimester and the woman’s medical history, with recommended intake ranging from 16 to 120 mg/day. Therefore, there are specific dietary supplements for pregnant women available. However, any intervention for the correction of anaemia should be guided by a healthcare professional who will determine the most appropriate approach based on the diagnosis, diet, and dietary supplementation needs.
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