NUTR2003 Lecture Notes - Lecture 5: Skeletal Muscle, Pre-Eclampsia, Spina Bifida
NUTR2003 LECTURE FIVE
Nutrition during pregnancy
• Key concepts of pregnancy
• Consequences of malnutrition during pregnancy
• Nutrient requirements
• Problems related to pregnancy
• Dietary guidelines during pregnancy
Key concepts:
• The mother's food habits and nutritional status before conception, as well as during pregnancy,
influence the outcome of the pregnancy
• Through the food a pregnancy woman eats, she gives her unborn child the nourishment required to
begin and sustain foetal growth and development
Objectives of pregnancy:
• To produce healthy, normal weight infants while minimising health risks to the mother
• To determine appropriate weight gain during pregnancy for normal, under and overweight women
• To recognise the additional energy, vitamin and mineral requirements for women during pregnancy
• To understand changing nutritional needs during pregnancy
What you do, eat or experience during the first 1000 days has lifelong consequences for your health.
-9 to 0 months (270 days) = Antenatal
0 to 12months (365 days) = Early postnatal/infancy
12 to 24 months (365 days) = Early childhood
A time of rapid growth: -9 months to 2 years. Plateau until teenage years, when growth 'spurts'.
A time of significant development - nutrition has a role in:
• Cognitive development
• Metabolic organs
• Body composition
• Immune maturation
• Digestive system
• Optimal growth -> healthy adults
• Altered growth -> disease
The environment has much more impact on your health later in life than your genes
• 20% lifelong health attributed to inherited genes
• 80% environment, nutrition, lifestyle
Time-related terms before, during and after pregnancy
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• Last menstrual period: 2 weeks before point of conception
• Periconceptional period: -4 to +4 weeks
• Perinatal period: week 20 to 40
• Trimester 1: mostly embryotic, then foetus until birth
• Death before week 20 = miscarriage/spontaneous abortion
• Death after week 20 = still birth
• Before week 20, viability of foetus is poor
• Before 34 weeks = very preterm
• Before 37 weeks = preterm
• Baby born at 40 weeks = term (optimal)
• After 40 weeks, up to 42 weeks = post-term baby
Summary of maternal anabolic and catabolic phases of pregnancy
Anabolic phase (0-20 weeks)
• Blood volume expansion, increased CO, build-up of fat, nutrient and liver glycogen stores
• Growth of some maternal organs
• Increased appetite, positive caloric balance
• Decreased exercise tolerance
• Increased levels anabolic hormones
Catabolic Phase (20+ weeks)
• Mobilisation of far and nutrient stores
• Increased production and blood levels of glucose, triglycerides and fatty acids; decreased liver
glycogen stores
• Accelerated fasting metabolism
• Increased appetite and food intake decline somewhat
• Increased exercise tolerance
• Increased levels catabolic hormones
The key challenges of nutrition during pregnancy
1. Nutritional status of a woman before becoming pregnancy: determines early embryo and placenta
development
2. Body weight of mother at conception: being underweight or overweight puts a pregnancy at risk,
and adversely affects later disease risk for the child
3. Nutritional requirements: increased in pregnancy, particularly for some vitamins and minerals
4. Total food intake: quality is key
Note: mental development = iron and iodine
Consequences of maternal under nutrition
Maternal:
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• Maternal death
• Infection
• Anaemia
• Lethargy and weakness
• Lactation failure
• Compromised bone health
Child:
• Foetal and neonatal death
• Intrauterine growth retardation
• Low birth weight
• Preterm birth
• Compromised immune function
• Birth defects
• Reduced mental development
• Increased risk chronic disease
3 Trimesters: Development
1. Week 1-12: Blastocyst implantation, embryo development, placenta formation, organ formation
2. Week 13-27: Foetus practising 'breathing' and movement, organ development
3. Week 28-40: Body and organ growth; rapid increase body fat
The Placenta: No direct mixing of maternal and foetal blood but oxygen and nutrients are exchanged,
and waste products are removed (foetal wastes carried by mother's veins). Maternal side of the
placental villi is bathed in nutrient-rich maternal blood. The placental villi absorb the nutrient molecules
and release them to the foetus via foetal capillaries. Mother's arteries bring fresh blood to foetus.
Embryonic and Foetal Development:
1. ZYGOTE: First 2 weeks. Size of full stop. Ready for implantation one week after fertilisation.
2. EMBRYO: 2-8 weeks. The placenta develops after implantation and begins to provide nourishment
to the developing embryo. An embryo five weeks after fertilisation is about 1/2 inch long.
3. FOETUS: 8-40 weeks (birth). After 11 weeks development just over an inch long. Notice the
umbilical cord and blood vessels connecting the foetus with the placenta.
4. INFANT: 1st year. Close to 20 inches length. From 8 weeks to term, infants grow 20 times longer and
50 times heavier.
Critical periods of growth and development: pre-programmed time periods during embryonic and
foetal development when specific cells, organs and tissues are formed and integrated or functional
levels established.
An adverse influence felt early (in critical period) permanently impairs development, and a full recovery
never occurs.
An adverse influence felt late temporarily impairs development, and a full recovery is possible
During embryonic development (2-8 weeks) many of the tissues are in their critical periods; events occur
that will have irreversible effects in the development of those tissues. In the later stages of
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