Pregnancy Anemia: Causes & Concerns - Essay Sample

Abstract

Anemia is the most frequent derailment of physiology in the world throughout the life of a woman. It is a serious condition in countries that are industrialized and in countries with poor resources. The main purpose of this manuscript is to give the right concern of anemia in pregnancy. The most common causes of anemia are poor nutrition, iron deficiencies, micronutrients deficiencies including folic acid, vitamin A and vitamin B12, diseases like malaria, hookworm infestation and schistosomiasis, HIV infection and genetically inherited hemoglobinopathies such as thalassemia. Depending on the severity and duration of anemia and the stage of gestation, there could be different adverse effects including low birth weight and preterm delivery. Treatment of mild anemia prevents more severe forms of anemia, strictly associated with increased risk of fetal-maternal mortality and morbidity.

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Keywords iron deficiency anemia, maternal-fetal implicationsAnemia is the most frequent derailment of physiology in the world throughout the life of a woman. It is a serious condition in industrialized and semi-industrialized countries and it becomes a very serious condition in poor resources countries. Anemia is a major public health problem, causing an unfavorable status in respect to upcoming pregnancy. Among fertile, nonpregnant women, approximately 40% have low iron reserves [1].

Introduction

Anemia is one of the world's leading cause of disability and thus one of the most serious global public health issues. In fact, it involves issues of morbidity and mortality, but it can be mostly the basis of the inability of the woman to react to a postpartum blood loss thus leading to serious consequences [2].

The main purpose of this manuscript is to give the right concern for anemia in pregnancy. The authors reviewed literature about anemia during gestation, providing updated and clear guidelines for the prevention and treatment of this condition, which, if not adequately treated, could lead to severe maternal and perinatal complications.

The authors tried to select recent articles about anemia in pregnancy from the database PubMed, whereas other data have been selected from international guidelines, such as WHO or CDC, in order to give updated information about this disorder. Most of these articles and guidelines have been released in the last five years. However, we also included some older studies, which seemed to be essential for describing completely the disease.

Following a complete review of literature, the authors enclose in this work risks associated with this disorder, all available diagnostic tools, different treatments and reasons why iron deficiency anemia should be prevented and treated.

Definition

Anemia is defined as the reduction in absolute number of circulating red blood cells (RBC)s, indirectly measured by a reduction in hemoglobin (Hb) concentration, hematocrit (Hct) or RBC count. WHO has defined it as Hb of <11 g/dl but, during pregnancy [3], definition of anemia is different depending on trimester (<11 g/dl in the first trimester, <10.5 g/dl in the second trimester, <11 g/dl in the third trimester) [4].

Prevalence

Iron deficiency is the most widespread nutritional deficiency in the world and it accounts for 75% of all types of anemia in pregnancy

In more than 80% of countries in the world, the prevalence of anemia in pregnancy is >20% [4]. The prevalence of anemia in pregnancy varies considerably because of the differences in social conditions, lifestyles and health seeking behaviors across different cultures. Anemia can affect pregnant women all over in the world (the global prevalence in pregnancy is estimated to be approximately 41.8%) with rates of prevalence that range from 35 to 60% for Africa, Asia and Latin America and it is reported to be <20% in industrialized countries [2-3,7-8]. The lowest estimated prevalence of anemia is of 5.7% in the USA and the highest is of 75% in Gambia and 65-75% in India [7, HYPERLINK "https://journals.sagepub.com/doi/full/10.2217/whe.15.35" 9].

Etiology

The most common causes of anemia are poor nutrition, deficiencies of iron, micronutrients deficiencies including folic acid, vitamin A and vitamin B12, diseases such as malaria, hookworm infestation and schistosomiasis, HIV infection and genetically inherited hemoglobinopathies, such as thalassemia [10]. There is also a possible association between Helicobacter species infection and anemia as reported in a study of Kibru in 2014 [11].

Iron deficiency is the most widespread nutritional deficiency in the world and it accounts for 75% of all types of anemia in pregnancy. It is due to the fact that diet in pregnancy is insufficient to supply iron requirement. It has high prevalence in developing countries, but it is also relevant in developed countries where other nutritional disorders have been almost eliminated [5, HYPERLINK "https://journals.sagepub.com/doi/full/10.2217/whe.15.35" 6]. Main manifestations of this disorder are pallor, glossitis and while patient may complain lassitude, weakness, anorexia, palpitation and dyspnea.

During pregnancy, there is a physiological hemodilution, with a peak during 20-24 weeks of gestation, and Hb varies through trimesters [7].

In fact, it is well established that there is a physiological drop in Hb in mid-trimester. This physiological drop is due to the higher increase in plasma volume, compared with RBC mass, which slightly increases during pregnancy. This physiological process produces relative hemodilution blood viscosity, helping the blood circulation in the placenta [12].

Moreover, during pregnancy, iron deficiency is relatively common because of the increased iron demand, with a mean iron requirement of 4.4 mg/day [13], and because many women start pregnancy with poor or deplete iron stores, so the amount of iron absorbed from diet, together with that mobilized from stores, is usually insufficient to meet the maternal demands imposed by pregnancy [13]. The serum ferritin level is a marker of depleted iron stores with a cut off value of <30 mg/l [2]. The iron availability is the rate limiting factor for RBC production by bone marrow. As iron deficiency occurs, iron stores in bone marrow decreases and serum ferritin level falls. As iron is essential in order to produce RBS in bone marrow, erythropoiesis starts to be impaired when serum iron is <50 mg/dl [8].

Beyond iron deficiency, a lack of other micro-nutrients can occur during pregnancy, influencing fetal-maternal outcome. For instance, folic acid depletion can increase risk of neural tube defects and calcium deficiency is associated with pre-eclampsia and growth restriction. Roughly 20-30% of women show a vitamin deficiency. Hence, iron supplementation is part of multiple micronutrients supplementation in pregnant women [14].

Maternal-Fetal Implications

Although one of the main target of WHO is prevention and treatment of anemia in pregnancy, it is still an underevaluated problem in developing countries with different adverse effects depending on the severity and duration of anemia and the stage of gestation. WHO classifies anemia mild when Hb is 10-10.9 mg/dl, moderate with Hb level of 7-7.9 mg/dl and severe when Hb level is <7 mg/dl [15]. Conclusions of several studies are controversial about the association of mild anemia and adverse maternal and fetal outcomes, resulting in the fact that a chronic mild anemia can lead to a normal course of the pregnancy and to a labor without any adverse consequences [9]. However, there is mounting evidence that iron deficiency may interfere with a defective myelination in infants, so that the resulting anemia produces long-lasting defects in mental development and performance that may further impair the child learning capacity [16]. Furthermore, treatment of mild anemia prevents moderate and severe forms of anemia, which are strictly associated with increased risk of fetal-maternal mortality and morbidity, requiring a treatment with higher doses of iron. Therefore, every case of anemia should be treated in pregnancy, in order to prevent adverse perinatal outcomes related to this disorder, considering a threshold <11 mg/dl, a good cut off to maintain optimal Hb (10-12 g/dl) throughout gestation with a better overall outcome.

International Nutritional Anemia Consultative Group, WHO and United Nations Childrens Fund reported that iron supplementation should be given in all pregnant women, as iron requirement during pregnancy is hard to meet only with diet, and in regions where iron deficiency anemia prevalence is >40%, supplementation should continue also in the postpartum period [5].

Even CDC suggests iron supplementation in pregnancy in order to prevent iron deficiency anemia (Box 1) [4].

Anemia in pregnant women has been considered as harmful for the fetal growth and fetal outcome. Low birth weight and preterm delivery have been persistently linked to anemia in pregnancy [21-23]. A significant increased risk of preterm birth in case of second trimester anemia has been demonstrated [21, HYPERLINK "https://journals.sagepub.com/doi/full/10.2217/whe.15.35" 22]. This could be explained to the state of chronic hypoxia consequent to anemia, which may induce a stress response, resulting in production of corticotropin-releasing hormone (CRH), elevated concentrations of which have been identified as a major risk factor of preterm birth. Additionally, the risk of preterm birth may increase owing to oxidative damage to erythrocytes and the fetoplacental unit.

Except for the first trimester, anemia in pregnant women has significantly increased the incidence of pre-term delivery. This association appears strongest in the third trimester. There are many studies showing similar association [24-27]. Kumar et al. and Monika et al. have found such an association when mothers are severely anemic.

Furthermore, an important issue is the increased risk for growth restrictions and impairment in mental and motor development in premature infants. Additionally, premature delivery is considered a frequent cause of death in newborns.

Rasmussen et al. have reported an inverse relationship between the second trimester Hb value and birth weight [23]. Third trimester Hb is an important factor in determining birth weight. It is known that rapid growth of fetus occurs in the third trimester. Iron and other micronutrient demands are highest in the same trimester as well. This may explain the association of third trimester Hb and low birth weight [30].

Other complications are related with anemia in pregnancy (Box 2). A study of Colomer that showed an increased risk (5.7-fold) of anemia in infants delivered from mothers who were anemic during labor, compared with nonanemic mothers [31]; and several articles reported a correlation between maternal anemia and lower Apgar scores at birth. In fact, in a study with 102 Indian mothers, Rusia demonstrated that a higher Hb level during labor was associated with better Apgar scores and subsequently decreased risk of birth asphyxia and child's disabilities [24].

Supplementing iron earlier and maintaining optimal Hb (10-12 g/dl) throughout gestation have better overall outcome regarding premature deliveries and low birth weight babies...