Chapter 26: Anemia During Pregnancy

INTRODUCTION

Anemia is one of the most common medical complications that occurs during pregnancy and is associated with numerous medical and obstetric complications. Women with anemia can present with vague complaints of fatigue, weakness, and dyspnea resulting from tissue hypoxia because hemoglobin, the oxygen carrying capacity of blood, is abnormally low. However, most women with mild-to-moderate anemia have no symptoms. The Centers for Disease Control (CDC) accounts for hemodilution of pregnancy and defines anemia as 11 g/dL in the first and third trimesters and 10.5 g/dL in the second trimester which reflects the greater expansion of plasma volume compared with red cell volume during the second trimester.¹ According to the World Health Organization (WHO), almost 42% of pregnant women worldwide are anemic with half of these women having iron deficiency as the cause.²

Anemia during pregnancy is associated with preterm birth, intrauterine growth restriction (IUGR), intrauterine fetal death, and adverse neonatal outcomes. A recent meta-analysis showed that women with moderate to severe anemia had a 50% greater risk to have a baby with IUGR.³ Babies born to women with anemia are more likely to be iron deficient and to develop anemia during infancy.⁴ Women with a multiple pregnancy or high parity are at higher risk for anemia, as are teenagers. Moreover, women of low socioeconomic status are at high risk for the development of anemia.⁵ Another recent risk factor is a history of bariatric surgery, as women who have experienced weight loss procedures are at increased risk for iron deficiency and vitamin B₁₂ deficiency.⁶

Prenatal vitamins, in particular iron and folic acid, are commonly prescribed to prevent pregnancy-related anemia. A recent review by Bhutta et al,⁷ concluded that supplementation with multiple micronutrients was just as effective as iron and folic acid supplementation alone for the prevention of anemia. These preparations contain lower doses of iron along with at least five different micronutrients that prevent other causes of anemia.

While common, anemia is not often as thoroughly evaluated as other medical complications because of a multitude of different classification systems and often overlapping categories that can be confusing. Physicians should always keep the clinical picture and patient history first and foremost when pursuing an evaluation for anemia. Anemia is often diagnosed on routine laboratory evaluation at entry into care, and because the vast majority of women with anemia during pregnancy are iron deficient, iron supplementation is prescribed without pursuing a more thorough evaluation. In this chapter, the evaluation and management of the most common causes of anemia during pregnancy will be reviewed, with a focus on a systematic approach to achieving a diagnosis efficiently in order to begin therapy expeditiously.

CLINICAL PRESENTATION

A 22-year-old G1P0 woman at 14 weeks gestational age presents to your clinic for prenatal care. She is excited about her pregnancy but appears anxious. Upon ...