Iron deficiency is the major cause of anemia followed by folate and B₁₂ deficiencies. In India, the prevalence of anemia is high because of (1) low dietary intake and poor iron (less than 20 mg/day) and folic acid intake (less than 70 mg/day), (2) poor bioavailability of iron (3–4 % only) in phytate- and fiber-rich Indian diet, and (3) chronic blood loss due to infection such as malaria and hookworm infestations [8]. In addition, teenage pregnancy, short birth intervals, and too many childbirths contribute to development of anemia in reproductive age group females.

Women with chronic mild anemia may go through pregnancy and labor without any adverse consequences, but those who had moderate anemia have reduced working capacity. Premature births are more common in women with moderate anemia and have higher morbidity and mortality due to antepartum and postpartum hemorrhage, pregnancy-induced hypertension, and sepsis [ICMR 1989]. Severe anemia may be decompensated and associated with circulatory failure. Cardiac decompensation usually occurs when Hb falls below 5.0 g/dl. The cardiac output is raised even at rest, and there is palpitations and breathlessness even at rest. Because of very low hemoglobin level, there is tissue hypoxia and lactic acid accumulation, leading to circulatory failure. If untreated, it may lead to pulmonary edema and death of the patient. A blood loss of even 200 ml in the third stage of labor produces shock and death. India data indicate that maternal morbidity rates are higher in women with Hb below 8.0 g/dl. Maternal mortality rates show a steep increase when maternal hemoglobin levels fall below 5.0 g/dl [8].

Irrespective of maternal iron stores, the fetus still obtains iron from maternal transferrin, which is trapped in the placenta and which, in turn, removes and actively transports iron to the fetus. Gradually, however, such fetuses tend to have decreased iron stores due to depletion of maternal stores. Adverse perinatal outcome in form of preterm and small-for-gestational-age babies and increased perinatal mortality rates have been observed in the neonates of anemic mothers. Iron supplementation to the mother during pregnancy improves perinatal outcome. Mean weight, Apgar score, and hemoglobin level 3 months after birth were significantly greater in babies of the supplemented group than the placebo group [9]. Most of the studies suggest that a fall in maternal hemoglobin below 11.0 g/dl is associated with a significant rise in perinatal mortality rate. There is usually a two- to threefold increase in perinatal mortality rate when maternal hemoglobin levels fall below 8.0 g/dl and eight- to tenfold increase when maternal hemoglobin levels fall below 5.0 g/dl. A significant fall in birth weight due to increase in prematurity rate and intrauterine growth retardation has been reported when maternal hemoglobin levels were below 8.0 g/dl [10].

Patients are largely asymptomatic in mild and moderate anemia.

There may be no signs especially in mild anemia. Common signs that may be present are: