Introduction
Pregnancy is one of the most critical and unique period in a woman’s life cycle. It is regarded as a “welcome event” for successful womanhood. A woman’s body changes dramatically during pregnancy; hence there is a strong need to balance these changes with an adequate and nutritious diet (King, 2010).
Pregnancy is often accompanied by a variety of nutritionally linked problems with symptoms that are sometimes very unpleasant and difficult to tolerate (Doerr, 2007). Cravings and aversions, which refer to a strong desire and strong dislike for certain food respectively, are common during pregnancy with complications such as nausea and vomiting (Walker & Verardi, 2009). These complications may cause not only discomfort during pregnancy but also interfere with the dietary intake of the pregnant woman and sometimes causing serious problems (Caplan, 2011).Also, unsatisfactory maternal nutrition has been reported to result from inadequate dietary intakes during pregnancy which have been attributed to ignorance and superstition.
The well-being of mother and the newborn infant is greatly determined by the nutrition of the expectant mother during pregnancy and it further influences health of the child during childhood and adulthood. According to Harding (2011), spontaneous abortion, impaired foetal growth, poor pregnancy weight gain, learning impairment and behavioural problems of the offspring are caused by inadequate nutrition during pregnancy. The majority of low birth weight (LBW) infants in developing countries are due to intrauterine growth retardation (IUGR i.e. less than the 10th percentile weight for gestational age), while most LBW infants in developed countries are due to preterm birth (Ramakrishnan, 2009). In developing countries, the most important determinants of IUGR stem primarily from the mother’s poor health and nutritional status (Wardlaw, Blanc & Ahman, 2014).
Thus, in the course of pregnancy, the quantity and quality of nourishment is of particular importance. Maternal malnutrition and other health hazards are serious problems facing developing nations.
Conceptual framework
Maternal diets during pregnancy have gained a lot of attention over the years. This is due to the recognition of the increased physiologic, metabolic and nutritional demand placed on the pregnant woman by her gravidity. The dietary intake of pregnant women needs to provide energy and nutrient for the mother, as well as the foetus (King, 2010). Studies have shown that inadequate dietary intake in pregnancy can lead to unfavourable outcomes.
Insufficient intake of nutritive food and dietary supplemental iron can lead to iron deficiency anaemia, with its attendant consequences, including an added risk for morbidity and labour complications (Scholl and Reilly, 2009).Diets and staple foods in sub-Saharan African are often deficient in macronutrients and micronutrients leading to multi-nutrient malnutrition and micro-nutrient deficiencies. These are often complicated by a high burden of preventable infectious diseases and helminthes infestations, with dire consequences among children and pregnant women (Abraham, Mehiza & Steyn, 2011).
Importance of healthy nutrition during pregnancy
Maternal nutritional status during pregnancy plays a more important role in determining foetal health and predisposition to some diseases, than genetic factors (e.g. a genetic predisposition to obesity). For example, studies show that in gestational surrogacy (where one woman bears a child conceived from the egg of another woman), factors relating to the recipient mother (the woman bearing the child) influence foetal health more so than those of the donor mother (the woman whose eggs were used) (Esmailzadeh, Sarareh & Azadbaklit, 2008).
Maternal nutrition during pregnancy also appears to have a “foetal programming” effect, that is, the foetus learns nutritional habits, which will influence it for the rest of its life, before it is even born. A foetus will also adapt its metabolism and other body systems to cope with different states of nutrition. For example, an under-nourished foetus, which does not receive enough macronutrients or energy, responds by reducing glucose and insulin production, which ultimately slows the rate of foetal growth and increases the risk of low birth weight. It may also alter the metabolism permanently and leave an individual predisposed to metabolic conditions such as diabetes. The foetus also adapts to under-nutrition by redirecting blood flow and therefore the supply of nutrients to protect the brain, at the expense of fully developing other organs including the kidneys, muscles and endocrine system (the system which regulates the body’s hormone production) (Ojofeitimi, Ogunjuyigbe, Sanusi, Orji, Akinlo & Liasu, 2008).
The nerves which regulate the foetus’s appetite are also programmed while it is developing in the womb and this affects an individual’s appetite regulation later in life. The foetal programming effect influences not only how much an individual consumes, but also their food preferences. Individuals who are programmed to consume high-fat, high-sugar diets in utero (whilst in the womb), also have a greater tendency to consume such diets throughout their life (Ojofeitimi, et al,2008).
Women at risk of poor nutrition during pregnancy
According to Chang, Dibley, Zhang, Zeng and Yan (2009), poor maternal nutrition is the key factor contributing to poor foetal development, which increases the risk that the baby born will be ill or die. All women experience increased nutritional requirements during pregnancy, and thus all women should ensure they are well informed about and attempt to maintain a healthy balanced diet before and during pregnancy. However, some women may find it harder to access or consume all the necessary components of a healthy diet throughout their life and during pregnancy. For example, those who are food insecure may be unable to access enough food to nourish themselves and their baby.
Women should also be aware that poor nutrition results from a complex range of factors, of which nutritional intake is just one. Infectious disease, physical labour and adolescent growth all create nutritional demands which may mean that a diet which meets the needs of a normal healthy woman is insufficient for a growing adolescent, a woman who is ill or one who engages in physical labour during pregnancy. Lifestyle habits such as smoking and drug use can limit the extent to which the body absorbs and uses nutrients and so these behaviours increase the risk of poor nutritional status during pregnancy (Ali, Azam & Noor, 2014).
Problems associated with poor nutrition during pregnancy
Health risks for the mother
Pregnant women who receive inadequate nutrition experience greater maternal morbidity (are more likely to be ill whilst pregnant) and have a higher risk of poor pregnancy outcomes (e.g. premature birth, miscarriage). According to Okwu, Ukoha, Nwachukwu and Agha (2007), they also have an increased risk of developing the following conditions:
- Anaemia;
- Infection;
- Lethargy and weakness;
- Lower productivity.
Health risks for the foetus and newborn baby
Okwu et al., (2007) stated that under-nutrition in pregnant women is associated with a range of detrimental effects to the developing foetus, including intrauterine growth retardation (IUGR) and low-birth weight. Maternal under-nutrition during pregnancy, IUGR and low birth weight are in turn associated with a range adverse outcome for the developing foetus and/or newborn baby, including an increased risk of: Stillbirth – some 50% of stillbirths in normally formed foetuses are attributable to IUGR;
- Premature birth;
- Perinatal mortality (death of the infant within seven days of birth) – infants who weigh <2.5kg are 5-30 times more likely to die within the first seven days of life compared to normal weight infants (≥2.5kg). Infants who weigh <1.5kg have a 70-100 times increased risk of dying within seven days of birth;
- Infant neurological, intestinal, respiratory and circulatory disorders;
- Birth defects;
- Underdevelopment of some organs;
- Cretinism (a congenital condition affecting the thyroid gland which results in lack of coordination, dull facial expression and dry skin);
- Brain damage.
Health risks for the child in the long-term
As pointed out above by Okwu et al (2007), maternal under-nutrition causes metabolic and other changes in the foetus, which program its metabolic responses following birth. For example, a foetus that is malnourished adapts by reducing insulin and glucose production. This is thought to program and permanently alter the individual’s glucose and insulin metabolism throughout their life and increase the risk of chronic nutritional disorders including type 2 diabetes mellitus, metabolic syndrome and obesity. For example, one study showed that the lower the birth weight of an infant, the higher the risk of developing type 2 diabetes. Men who were born at a very low weight were seven times more likely to develop diabetes compared to men born at a high weight.
However, the effects of maternal under-nutrition vary depending on the stage of pregnancy at which under-nutrition is experienced. For example, one study reported that exposure to maternal malnutrition in the first trimester of pregnancy was associated with an increased risk of obesity and coronary heart disease, while malnutrition in the second or third trimester was associated with poor glucose metabolism. The offspring of women who experienced under-nutrition during pregnancy according to Oni and Tukur (2012) have an increased risk of developing:
- Metabolic disorders including:
- Type 2 diabetes mellitus;
- Dyslipidaemia (abnormal concentration of lipids in the blood);
- Glucose intolerance (a pre-diabetes condition in which the body is unable to metabolise glucose normally)
- Impaired energy homeostasis (when the body does not function as it should to regulate its energy levels);
- Obesity;
- Mitochondrial dysfunction (dysfunction of the mitochondria, which is found in the cell nucleus and provides the cell energy);
- Oxidative stress (a state in which the body has too many reactive molecules which can cause cell damage);
- Ageing;
- Cardiovascular disorders including:
- Hypertension;
- Atherosclerosis (narrowing of the blood vessels);
- Stroke; and
- Coronary heart disease;
- Osteoporosis;
- Breast cancer;
- Chronic obstructive lung disease;
- Chronic kidney failure;
- Polycystic ovarian syndrome;
- Psychiatric disorders including schizophrenia;
- Organ dysfunction or abnormal development of organs including the testes, ovaries, brain, heart, liver, small intestine and mammary gland;
- Reduced adolescent health, especially for females;
- Reduced health during adulthood;
- Infectious disease.
Individuals who are born at a low weight have a greater risk of poor development outcomes during infancy and childhood. The mother’s nutritional intake before, during and after pregnancy influences their child’s immediate and long-term mental development and performance.
The greatest brain growth occurs between the 3 months before birth and 2 years of age. It is at these stages that the development of the brain’s nerve system and the connection between nerves is at its peak and so the brain requires the most energy to maintain its growth. The nerve system made during this time impacts the way the brain is structurally and functionally organised (cortical organisation) throughout life. According to Oni and Tukur (2012) poor foetal development has been associated with the following adverse health and development outcomes later in life:
- Poor performance at school, learning and developing skills;
- Reduced ability to perform physical work; and
- Reduced economic productivity.
Health risks associated with micronutrient deficiency during pregnancy
There are also numerous maternal and foetal health risks associated with micronutrient deficiency during pregnancy, that is, deficiency in particular micronutrients such as folate, and vitamin B12.
Health risks for the mother
Maternal health risks which may arise as a result of deficiency in particular micronutrients according to Okwu et al (2007) include:
- Vitamin B12 deficiency is associated with the following risks for pregnant women:
- Anaemia and its symptoms;
- Neurological complications;
- Vitamin K deficiency is associated with blood clotting disorders, including increased clotting time which presents particular risks during delivery when women lose substantial amounts of blood, even when blood clotting functions normally;
- Iron deficiency during pregnancy is associated with iron deficiency anaemia;
- Iodine deficiency is associated with poor pregnancy outcomes including:
- Miscarriage;
- Stillbirth;
- Zinc deficiency is associated with:
- Pre-eclampsia (high blood pressure and urinary protein concentrations during pregnancy);
- Premature rupture of membranes (when a woman’s amniotic sac or pregnancy waters break before she experiences contractions); and
- Preterm delivery.
- Magnesium deficiency increases the risk of:
- Pre-eclampsia;
- Pre-term delivery.
Health risks for the baby
A woman’s deficiency in particular micronutrients whilst she is pregnant has detrimental effects on particular aspects of foetal development. Foetal health risks which arise as a result of deficiency on particular micronutrients as identified by Oni and Tukur (2012) include:
- Maternal vitamin D deficiency is associated with foetal rickets (a condition which weakens the bones);
- Maternal folate deficiency is associated with an increased risk of neural tube defects in the infant;
- Maternal iodine deficiency is associated with the following complications in the infant:
- Congenital abnormalities;
- Increased risk of infant mortality;
- Neurological cretinism (a congenital condition of poor thyroid hormone secretion which impairs cognitive development);
- Mental deficiency;
- Spastic diplegia (spastic paralysis of the limbs) and squint;
- Myxoedymateous cretinism (a type of cretinism in which physical development is impaired) and dwarfism (very short stature);
- Psychomotor effect (affected movement).
- Maternal zinc deficiency is associated with:
- Foetal growth retardation;
- Congenital abnormalities.
Recommended diet for women during pregnancy
Ajose, Adelakun and Ajewole (2014) stated that good nutrition during pregnancy, and enough of it, is very important for pregnant women and their babies to grow and develop. Pregnant women should consume about 300 more calories per day than they did before they became pregnant.
Ufuoma (2014) stated that additional protein is necessary for the growth of the foetus and new maternal tissues to prepare the mother for lactation, 14g of protein daily is needed during the second half of pregnancy; which should be of good quality such as fish, milk, meat, etc. Although nausea and vomiting during the first few months of pregnancy can make this difficult, pregnant women should try to eat a well-balanced diet and take prenatal vitamins to increase tissue synthesis. Here are some recommendations to keep pregnant women and their babies healthy. Pregnant women should:
- Eat a variety of foods to get all the nutrients you need. Recommended daily servings include 6-11 servings of breads and grains, two to four servings of fruit, four or more servings of vegetables, four servings of dairy products, and three servings of protein sources (meat, poultry, fish, eggs or nuts). Use fats and sweets sparingly.
- Choose foods high in fibre that are enriched, such as whole-grain breads, cereals, pasta and rice, as well as fruits and vegetables.
- Make sure they are getting enough vitamins and minerals in their daily diet while pregnant. They should take a prenatal vitamin supplement to make sure they are consistently getting enough vitamins and minerals every day.
- Eat and drink at least four servings of dairy products and calcium-rich foods a day to help ensure that they are getting 1000-1300 mg of calcium in your daily diet during pregnancy.
- Eat at least three servings of iron-rich foods, such as lean meats, spinach, beans, and breakfast cereals each day to ensure you are getting 27 mg of iron daily.
- While pregnant, women will need 250 micrograms of iodine a day to help ensure the baby’s brain and nervous system They should choose from a variety of dairy products — milk, cheese (especially cottage cheese), yogurt — as well as baked potatoes, cooked navy beans, and limited amounts — 8 to 12 oz per week — of seafood such as cod, salmon, and shrimp. Also the use of iodized salt is recommended.
- Pregnant women need foods rich in calcium and phosphorus which are needed for the formation of bones and teeth. The formation of teeth starts early in prenatal life, so it is important that the mother gets sufficient calcium for the beginning of pregnancy.
- Choose at least one good source of vitamin C every day, such as oranges, grapefruits, strawberries, honeydew, papaya, broccoli, cauliflower, Brussels sprouts, green peppers, tomatoes, and mustard greens. Pregnant women need 70 mg of vitamin C a day.
- Choose at least one good source of folic acid every day, like dark green leafy vegetables, veal, and legumes (lima beans, black beans, black-eyed peas and chickpeas). Every pregnant woman needs at least 0.4 mg of folic acid per day to help prevent neural tube defects such as spina bifida.
- Choose at least one source of vitamin A every other day. Sources of vitamin A include carrots, pumpkins, sweet potatoes, spinach, water squash, turnip greens, beet greens, apricots, and cantaloupe.
Foods to avoid by women during pregnancy
Ojofeitimi et al (2008) warned that women should avoid the following foods during pregnancy:
- Avoid alcohol during pregnancy: Alcohol has been linked to premature delivery, mental retardation, birth defects, and low birth weight babies.
- Limit caffeine: Pregnant women should limit caffeine consumption to not more than 300 mg per day. The caffeine content in various drinks depends on the beans or leaves used and how it was prepared. An 8-ounce cup of coffee has about 150 mg of caffeine on average while black tea has typically about 80 mg. A 12-ounce glass of caffeinated soda contains from 30-60 mg of caffeine. Remember, chocolate (especially dark chocolate) contains caffeine — sometimes a significant amount.
- Avoid saccharin: The use of saccharin is strongly discouraged during pregnancy, because it can cross the placenta and may remain in foetal tissues.
- Reduce fat consumption: There should be decrease in the total amount of fat that pregnant women eat to 30% or less than the total normal daily calories. For a woman eating 2000 calories a normal a day, this would be 65 grams of fat or less per day.
- Limit cholesterol intake to 300 mg or less per day.
- Pregnant women should not eat shark, swordfish, king mackerel, or tilefish (also called white snapper), because they contain high levels of mercury.
- Avoid raw fish, especially shellfish like oysters and clams.
References
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