Under-Nutrition Before and During Pregnancy

• Introduction
• Health risks associated with malnutrition before pregnancy
  • Health risks for the mother
  • Health risks for the foetus and newborn baby
  • Health risks for the child in the long-term
• Health risks associated with micronutrient deficiency before pregnancy
  • Health risks for the mother
  • Health risks for the baby
  • Health risks for the child in the long-term

 

• Health risks associated with malnutrition during pregnancy
  • Health risks for the mother
  • Health risks for the foetus and newborn baby
  • Health risks for the child in the long-term
• Health risks associated with micronutrient deficiency during pregnancy
  • Health risks for the mother
  • Health risks for the baby

Introduction

There are a range of adverse health effects associated with maternal under-nutrition. It can affect both the pregnant woman and developing baby in the short and long-term.

Under-nutrition can be classified as either:

• malnutrition; or
• micronutrient deficiency.

Malnutrition occurs when an individual consistently consumes less energy (measured in calories and obtained from proteins and carbohydrates) than they expend. Malnutrition results in the individual being underweight and experiencing greater ill-health.

Micronutrient deficiency is a condition which occurs when an individual consumes enough food overall, but does not consume enough of the specific micronutrients they need to maintain the growth and function of specific body parts and systems. For example, calcium deficiency can affect the growth of bones and teeth.

Health risks associated with malnutrition before pregnancy

A woman’s nutritional status at the time she becomes pregnant influences her health during pregnancy and the health of her baby. It is determined largely by her nutritional intake before pregnancy. If a woman is under-nourished prior to conception because she does not eat enough, she may be malnourished and underweight at the time she conceives. This will have an ongoing effect on her nutritional status throughout the pregnancy. Her nutritional status at the time she becomes pregnant is also an important factor influencing the health of the foetus, as well as the long term health of the infant.

For more information, see Importance of Nutrition Before Pregnancy.

Health risks for the mother

Women who are under-nourished (have a BMI of <18.5kg/m²) at the time of conception are unlikely to improve their nutritional status during pregnancy, when their bodies have additional demands due to the growing baby. They may fail to gain sufficient weight during pregnancy and have a higher risk of maternal mortality (dying whilst pregnant) than normal weight women.

Health risks for the foetus and newborn baby

Under-nourished women may also lack the nutritional stores required to support embryo growth. Embryo refers to a fertilised egg, before it begins to take on human characteristics (at which stage it is referred to as a foetus). In the first few days after conception the embryo exists in the woman’s womb but has not yet implanted into the lining of the womb where it will grow throughout the pregnancy. This is known as the pre-implantation period and is the period of pregnancy in which cells divide and replicate most rapidly. Maternal malnutrition can adversely affect the division and replication of cells in the embryo at this stage, impairing its development. Impaired embryo development in turn adversely effects the development of the foetus in the later stages of pregnancy.

A woman’s nutritional status at the time she becomes pregnant also influences the differentiation of cells in the embryo into foetal and placental cells. When the embryo implants into the wall of a woman’s uterus, it develops two types of cells, those that will become the foetus and those which will become the placenta (the structure which nourishes and supports the foetus during pregnancy). In undernourished women, a greater number of cells are likely to form the placenta compared to the foetus, meaning that the foetus begins its life smaller than it should do. This can lead to restricted foetal growth and increases the risk of the baby being born at a low-birth weight (<2.5kg). Low birth weight is in turn associated with a range of adverse outcomes in childhood and later in life.

Image courtesy of Blausen Medical Communications. Contact Andrew Walbank.

Foetal development is also affected by maternal nutritional status before pregnancy. It is during the first five weeks of pregnancy when the foetus develops most of its organs (e.g. heart, brain, lungs). At this stage the foetus is most vulnerable to the mother’s malnutrition. Nutritional deficiencies at this time may retard the growth of the foetus’s organs. As the woman is usually unaware she is pregnant at this early stage, she can only ensure she is well nourished by eating properly before she becomes pregnant.

Health risks for the child in the long term

When a foetus is malnourished in the early (and later) stages of pregnancy it may also have a lifelong programming effect which predisposes the baby to chronic health conditions later in life. For example, the foetus may adapt its metabolism to cope with malnutrition by reducing the amount of insulin and glucose produced. Such adaptation has been shown to permanently program the metabolic system and increase the risk of chronic health conditions later in life such as type 2 diabetes.

Health risks associated with micronutrient deficiency before pregnancy

Micronutrient status at the time of conception is also determined by historic nutrient consumption, and deficiency in one or more micronutrients can detrimentally affect the health of the mother and her baby.

Health risks for the mother

Women who experience deficiencies in specific micronutrients before pregnancy have an increased risk of the following health conditions:

• Iron-deficiency – is a common cause of anaemia which is thought to affect up to 20% of pregnant women in industrialised countries. Anaemia often develops during pregnancy as a result of long-tem under-consumption of iron. Anaemia in turn increases the risk of:
  • Maternal morbidity and mortality (illness or death during pregnancy) for example women with anaemia have an increased risk of death from bleeding during childbirth;
  • Preterm birth;
  • Neurological dysfunction;
• Vitamin A deficiency – is associated with night-blindness (difficulty seeing at night) in pregnancy (although this is mainly an problem in developing countries). Night-blindness is influenced both by the availability of vitamin A stores in the liver (which develop through pre-pregnancy consumption) and vitamin A consumption during pregnancy;
• Increased risk of micronutrient deficiency during pregnancy – women who have micronutrient deficiencies when they become pregnant are unlikely to improve their micronutrient status during pregnancy. They are therefore more likely to experience a range of health complications which are associated with micronutrient deficiency during pregnancy.

Foetal and neotnatal health risk

Maternal deficiency in particular micronutrients can also affect the development and health of the foetus. For example:

• Folate deficiency in early pregnancy is associated with deficits in the development of the neural tube (the tube from which the brain and spinal cord develop) which may result in conditions such as spina bifida. Folate status in early pregnancy depends on preconception nutrition;
• Calcium deficiency which restricts foetal skeletal development may occur if a woman does not have adequate calcium stores in her bones (developed through long-term calcium consumption), from which the foetus can receive this important micronutrient; and
• Iron deficiency which causes maternal anaemia is associated with intrauterine growth retardation (restricted foetal growth) and low birth weight. Iron deficiency can also affect the absorption of folate. As folate absorption is most critical in the early stages of pregnancy, ensuring adequate preconception iron status is also important.

Health risks for the child in the long-term

The effects of pre-pregnancy micronutrient deficiency may be long term. For example, neural tube defects often cause life long health conditions such as spina bifida. Those born at low birth weight have an increased risk of impaired physical and mental development. They may grow shorter than and have more learning difficulties than babies born at a healthy weight (≥2.5kg).

 

Health risks associated with malnutrition 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). 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

Under-nutrition in pregnant women is associated with a range of detrimental effects to the developing foetus, including intrauterine growth retardation (under-growth) and low-birth weight.Maternal under-nutrition during pregnancy, IUGR and low birth weight are in turn associated with a range adverse outcomes 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 mentioned above, 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 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.

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 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 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.

More information

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For more information about pregnancy, including preconception advice, stages of pregnancy, investigations, complications, living with pregnancy and birth, see Pregnancy.

For more information on nutrition, including information ontypes and composition of food, nutrition and people, conditions related to nutrition, and diets and recipes, as well as some useful videos and tools, see Nutrition.

For more information about pregnancy planning, including importance of nutrition before pregnancy, being under-weight, being overweight, tobacco exposure and alcohol consumption, see Pregnancy Planning (Preconception Advice).

 

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