1.1 Background to the Study
Micronutrients encompass vitamins and minerals which are essential for human development and functioning. They are needed in small amount. Micronutrients are well known to play an important role in the maintenance of health. Alterations in maternal – fetal disposition of some essential nutrients could be a potential health risk for the mothers as well as the fetus. Micronutrient malnutrition is primarily related to inadequate dietary intake and pregnancy places women at risk of nutritional problems due to increased need for both macro and micronutrients during pregnancy. Deficiencies of micronutrients (iron, selenium and zinc) during pregnancy continue to be a problem of considerable magnitude in most developing countries of the world. Child birth remains one of the biggest health risks for women especially in the developing countries. Fifteen hundred women (1,500), die every day during delivery, which is a half a million mothers every year (UNICEF, 2009). The WHO, (2007) estimated that about 80% of maternal deaths are due to direct causes which are hemorrhage, sepsis, eclampsia and unsafe abortion. About 20% are due to indirect causes including anemia, malaria and heart disease (WHO, 2007). The micronutrient status of mothers can affect hemorrhage, anemia, eclampsia, sepsis and perhaps malaria. In addition, micronutrients can reduce morbidity. Adequate micronutrient nutrition for pregnant women is critical for the health and survival prospects of both mothers and newborns. Micronutrient deficiencies of mothers increase their health risks as well as that of their babies. The high incidence of micronutrient deficiencies in pregnant women predisposes them to high maternal mortality especially in the developing countries. In Africa maternal mortality is estimated at 820 per 100,000 births. In Nigeria, the maternal mortality ratio is 1,100 deaths per 100,000 live births and the lifetime risk of maternal death, at 1 in 8. Approximately 1 in every 9 maternal deaths occurs in Nigeria alone (UNICEF, 2009).
Iron is an essential micronutrient which helps in normal human physiology. It is an integral part of many proteins and enzymes that maintain good health. Iron is essential for regulation of cellular growth and differentiation. It is also an essential component of protein involved in oxygen transport (Dallman, 1986). Iron deficiency anemia affects over 2 billion people and the world health organization estimates that a disproportionate percentage of iron deficiency anemia occur in low income countries, accompanied by adverse pregnancy outcomes such as preterm birth, low birth weight, and increased maternal mortality (UNICEF, 2009). It has been estimated that over half the pregnant women in the world have a hemoglobin level indicative of anemia. In Africa the prevalence ranges from 35% to 72% (UNICEF, 2009). The 2003 Nigeria Demographic and Health Survey conducted in Nigeria estimates that 35% of pregnant women were iron deficient (Maziya et al., 2003). Iron deficiency anemia, (especially severe form) has been shown to the associated with increased maternal mortality. The mild form of iron deficiency anemia may increase the rate of premature delivery and prenatal mortality (Carriaga, Skikne, Finley, Cutler and Cook, 1991).
Zinc is an essential micronutrient that participates in carbohydrate and protein metabolism. Zinc is required for cellular division and differentiation, and is an essential nutrient for normal embryogenesis. Zinc plays an important role in growth and development. It takes part in deoxyribonucleic and ribonucleic synthesis. It also interacts with hormones important in bone growth such as testosterone, insulin and the thyroid hormone. Through these functions, zinc plays an important role in intrauterine growth (Nishi, 1996). Several studies have shown an association between maternal plasma zinc levels and birth weight (Neggers et al., 1990). Studies have also shown how maternal serum zinc concentrations are associated with increased incidence of foetal malformations and foeto-maternal complication (Scholl, Hediger, Schall, and Khoo, 1993). Maternal morbidities such as pregnancy induced hypertension, prolonged labour and pre-and post-term deliveries may be increased in zinc deficient pregnant women. However, zinc deficiency is one of the most common nutritional problems of pregnant women especially in the developing countries. Caulfield, Zavaleta, Shankar, and Merialdi (1998) estimated that 82% of pregnant women worldwide have inadequate intakes of zinc to meet the normative needs of pregnancy. Zinc deficiency was reported as 43% in pregnant women in a food consumption and nutrition survey in Nigeria (Maziya et al., 2003).