What You Should Know About Iron During Pregnancy

Deficiency of iron during pregnancy

Iron deficiency anemia is the most prevalent nutritional deficiency that affects 14% of the pregnant women in developed countries and as much as 56% (or about 35% to 75%) women in developing countries, according to statistics released by World Health Organization (WHO) (1). Healthcare providers around the world recommend all reproductive aged women to consume sufficient quantities of iron-rich foods as well as supplemental iron in order to maintain an uneventful pregnancy. In addition, hemoglobin levels of an expecting mother should be periodically assessed throughout the pregnancy in order to detect iron deficiency as early as possible.

What is anemia during pregnancy?

Anemia refers to compromised capacity of red blood cells to carry oxygen to the periphery. According to WHO, a woman is considered anemic if hemoglobin levels during pregnancy are less than 110 g/L or 115 g/L depending upon the stage and trimester of pregnancy; however, hemoglobin concentration of less than 100g/L is considered severe anemic regardless of the stage of pregnancy (1). A Study reported in the Clinics in Laboratory Medicine also suggested that anemia in pregnancy should also be diagnosed by carefully assessing the hematocrit (the ratio of the volume of red blood cells to the total volume of blood) values in addition to hemoglobin. This is mainly because plasma volume shifts throughout the different stages of pregnancy; thereby aggravating the risk of physiological anemia (anemia in the neonatal period) (2). A hematocrit value of less than 33% is considered anemic and may aggravate the risk of a variety of complications.

Who is at risk of developing iron deficiency anemia during pregnancy?

According to Horowitz and associates (2), the bodily demand for iron increases up to three times during pregnancy. Part of this increased demand is due to increased iron consumption (for fetal development and placental functions), and partly due to changes in the metabolic functions (such as increased plasma volume, erythropoiesis etc.). Therefore, under ideal circumstances, women must maintain a sufficient iron reserve of at least 300 mg before becoming pregnant (4).

Here are some factors that can make you vulnerable to develop iron deficiency during pregnancy (5, 11):

  • Poor Socioeconomic status
  • Iron deficiency before conception
  • Multiple pregnancies
  • More than one pregnancy (multipara)
  • Inadequate spacing between two pregnancies

The risk of developing iron deficiency also increases during the postpartum period. Regardless of the nature of childbirth, an average woman can become iron deficient within one week of giving birth if she fails to consume a sufficient amount of iron supplements during pregnancy. Immediate steps should be taken to overcome iron deficiency to minimize the risk of serious health issues in both mother and the child.

Here are some factors that can make you vulnerable to develop iron deficiency during the postpartum period:

  • Premature delivery
  • History of uncontrolled hypertension during pregnancy
  • Post-term child birth
  • History of recurrent episodes of bleeding after 28 weeks of pregnancy
  • Excessive blood loss during child birth
  • Unresolved or undetected deficiency of iron during pregnancy
  • Cesarean section or instrumental delivery
  • Women with BMI greater than 24 before becoming pregnant
  • Placenta previa (a condition in which the placenta partially or wholly blocks the neck of the uterus, thus interfering with normal delivery of a baby)

Pregnancy and the need of supplemental iron

Throughout the stages of pregnancy iron requirements change. The demand for iron decreases (due to the lack of menstruation) and then increases gradually soon after the first trimester begins, and reaches it’s peak during the last trimester.

Despite pregnancy-induced amenorrhea (or lack of menstrual cycles), significant amounts of iron is lost from the maternal body due to following reasons (3, 4):

  • Transfer of iron into the fetal body for development and growth. For example, a 3.5kg fetus requires 270mg iron to maintain necessary metabolic functions. This iron is absorbed from the mother’s body.
  • Around 230mg of iron is lost via urine, gut and the skin of the mother, an obligatory loss.
  • Placenta and umbilical cord stores up to 90mg iron.
  • An average woman loses up to 200mg of iron due to blood loss during child birth.

In short, the total iron loss during pregnancy and postpartum period is as high as 1000 mg (3, 4)

Average added iron requirement according to trimesters

ThirdMore than 6

According to the study reported in the Journal of American Diet Association (3, 5), investigators suggested that an average woman must consume at least 27mg iron per day during pregnancy for an uneventful gestation.

What are the consequences of iron deficiency during pregnancy and the postpartum period?

Poor iron intake in pregnancy can aggravate the risk of developing iron deficiency in women, which can lead to a wide variety of complications such as:

Pregnancy related complications:

Excessive tiredness and exhaustion are very normal throughout the pregnancy, but anemic women tend to experience more aggravated fatigue and low energy. This can affect mood, productivity and overall health during pregnancy. Although, absorption of iron from the gut increases during the pregnancy by up to 90%, yet even with an iron enriched diet, the maximum iron absorption is only 3-4 mg/d (7).

Common symptoms of iron deficiency anemia during pregnancy are:

  • Dizziness, chest pain
  • Headaches
  • Cold extremities and pale skin
  • Frequent infections

Severe and poorly managed iron deficiency anemia can aggravate the risk of circulatory imbalance, poor oxygen delivery to the tissues, elevated heart rate, palpitations, arrhythmia (abnormal heart rhythm) and even heart failure (8). Other notable complications include, delayed recovery, sepsis, shock and increased risk of urinary tract infections.

Post-partum maternal complications:

Regardless of the mode of childbirth, a woman is at high risk of developing iron deficiency anemia in the absence of supplemental iron intake during the pregnancy. Common complications include:

  • Tiredness and effect on lactation: Anemia-induced fatigue can compromise lactation, since the new mother is too tired to fulfill the demands of the baby. If such practice prolongs, it may lead to insufficient milk syndrome (8).
  • Less antibodies in breastmilk: A newborn obtains immunity through a mother’s milk, as it is enriched with antibodies that are transferred to the child (boosting the immune system and preventing from infections of the gut and respiratory system). When the mother becomes anemic, concentration of antibodies and complement proteins in milk decreases to the point in which the child doesn’t develop sufficient immunity (8).
  • Postpartum depression: Low levels of hemoglobin can induce depression in a mother, which will ultimately affect the baby (9).

What are the consequences of maternal iron deficiency on fetal development?

According to a study reported in the American Journal of Clinical Nutrition, women who develop iron deficiency anemia during first and second trimester are twice as likely to give birth to a premature baby. In addition, iron deficient mothers are three- times more likely to give birth to babies with low-birth weight.

The third trimester of pregnancy marks the rapid development of the central nervous system, which continues up to 2 years post-birth. However, iron deficiency can compromise brain development, especially the hippocampus (a part of brain associated with memory, learning and cognition). In poorly managed cases, this may lead to neurocognitive dysfunction and permanent consequences.

Post-natal Complications

After birth, the gut of the newborn is unable to absorb sufficient quantities of iron from the breast milk until 6-9 months post-birth (9). Therefore reserved body stores of iron is the only available form of iron for the growth and development in young babies. The reserved stores are obtained from the mother’s body during pregnancy. Since premature babies were unable to obtain maximum iron from their mother, their development is usually compromised (10). Gestational diabetes (a type of diabetes developed while pregnant) and iron deficiency anemia in the mother may also increase the risk for iron deficiency in the child, even with full term birth.

How to screen pregnant mothers for iron deficiency anemia?

Healthcare providers recommend periodic screening throughout the pregnancy via CP (complete picture) and MCV (mean corpuscular volume) to detect microcytic anemia (that is caused by iron deficiency). In areas where hemoglobin disorders are common, ferritin levels should also be assessed for more definitive diagnosis (3, 11).


  1. ACC/SCN (United Nations Administrative Committee on Coordination/Standing Committee on Nutrition) Fifth report on the world nutrition situation: Nutrition for improved development outcomes. Geneva, Switzerland, accscn@who.org, 2004.
  2. Horowitz, K. M., Ingardia, C. J., & Borgida, A. F. (2013). Anemia in pregnancy. Clinics in laboratory medicine, 33(2), 281-291.
  3. Khalafallah, A. A., & Dennis, A. E. (2012). Iron deficiency anaemia in pregnancy and postpartum: pathophysiology and effect of oral versus intravenous iron therapy. Journal of pregnancy, 2012.
  4. Panel on Micronutrients, Food and Nutrition Board, Institute of Medicine—National Academy of Sciences. Dietary reference intakes: recommended intakes for individuals, vitamins, 2001.
  5. Khalafallah, A. A., & Dennis, A. E. (2012). Iron deficiency anaemia in pregnancy and postpartum: pathophysiology and effect of oral versus intravenous iron therapy. Journal of pregnancy, 2012.
  6. Institute of Medicine. Dietary Reference Intakes (DRIs) for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. National Academy Press, Washington, DC, USA, 2002
  7. McArdle, H. J., Gambling, L., & Kennedy, C. (2014). Iron deficiency during pregnancy: the consequences for placental function and fetal outcome. Proceedings of the Nutrition Society, 73(01), 9-15.
  8. Bothwell, T. H. (2000). Iron requirements in pregnancy and strategies to meet them. The American journal of clinical nutrition, 72(1), 257s-264s.
  9. Bodnar, L. M., Scanlon, K. S., Freedman, D. S., Siega-Riz, A. M., & Cogswell, M. E. (2001). High prevalence of postpartum anemia among low-income women in the United States. American journal of obstetrics and gynecology, 185(2), 438-443.
  10. Scholl, T. O., Hediger, M. L., Fischer, R. L., & Shearer, J. W. (1992). Anemia vs iron deficiency: increased risk of preterm delivery in a prospective study. The American journal of clinical nutrition, 55(5), 985-988.
  11. Baker, R. D., & Greer, F. R. (2010). Diagnosis and prevention of iron deficiency and iron-deficiency anemia in infants and young children (0–3 years of age). Pediatrics, 126(5), 1040-1050.
  12. Breymann, C. (2005). Iron deficiency and anaemia in pregnancy: modern aspects of diagnosis and therapy. European Journal of Obstetrics & Gynecology and Reproductive Biology, 123, S3-S13.

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