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Study Theme 1: Nutrition during Pregnancy
Pregnancy and Lactation
Prelude to Pregnancy
 Pregnancy is a natural physiological process - the
man & woman’s nutrition affect fertility
o Female nutrition affects the development
and growth of the infant
o It is important for women to have high
quality nutrients before, during and after
pregnancy
o Mother’s nutrition influences the size, health and future health of the baby
o Healthy & good quality placenta determines nutritional outcomes of the baby
 The importance of women’s health before conception
o Influences the ability to conceive
o Impact the health of the infant
o Impact her own health later
o Ability to cope with the physical, emotional and mental demands
Healthy Habits to be promoted before Conception
 Achieve and maintain a desirable weight
o To decrease risks to her and the infant
o Establish appropriate eating habits that are
maintained throughout pregnancy
 Selection of a nutritionally adequate diet: Folate,
iron and calcium
 Being physically active
 Receive regular medical care
 Avoid harmful environmental factors
Physiological Changes during Pregnancy
Maternal
 Physiological adaptations to pregnancy
o Increases absorption of essential nutrients
o Lowered excretion
o Adaptation of her metabolism
o Uterus and supporting muscles - expand
o Breast size, blood volume and BMR increases
o Additional work load: CVS, kidneys and lungs
o Gastro intestinal motility decreases
 If the mother was well nourished before pregnancy – reserves are present in the body
o In certain cases full-term normal babies are born without any modification to the mothers diet
o It is important that nutrient stores of the mother are not depleted through lactation
Placental
 The placenta develops in the uterus, along with the amniotic sac and the umbilical cord
 New endocrine organ
o Interweaving of foetal and maternal blood vessels embedded in the uterine wall
o Produces and secretes a variety of hormones and proteins
...
5 cm
o Features
 Outer layer (CNS & Skin)
 Middle layers (Muscle layer & internal organs)
 Inner layers (Glands & mucus membranes)
Growth
 Next 7 months
 Increase in quality and quantity of nutritional needs
 Deficiency: Results in Premature births
 Three phases:
o Hyperplasia - an increase in cell number
 NB nutrients are Folate, VitB12
 Synthesis of RNA & DNA at cell division
o Hypertrophy - increase in cell size (growth)
 NB nutrients are AA & B6
 Protein synthesis
 Less hyperplasia & more hypertrophy
 Cells reach maturity
 Consequences of deficiency / external shock vary:
o Early: Spontaneous abortions
o Later (during cell diff): Congenital disorders
o Post diff: No effect, may only be on growth
 Tissue increase during pregnancy
o T1: Mainly mother
o T2: Both mother & foetus
o T3: Mainly foetus



Nutrients transferred during pregnancy:
o In spite of mothers stores: Folic Acid, Fe, VitC, VitB12
o In competition with mother: Vit B1, B2, B6, D
o Priority for mother: Vit A, E

Neural Tube Defects
 Anencephaly – No brain (the upper end of neural tube fails to close and no brain develops)
o Infants die shortly after birth
 Spina Bifida – Split spine
o Incomplete closure of the spinal cord
o The meninges membranes often protrude as a sac
o Often results in paralyses varying in degree of spinal cord damage
o Severe cases lead to death
 Increased risk if:
o Previous pregnancy affected
o Maternal diabetes type1
o Maternal use of anti-seizure medicines
o Maternal obesity
o Exposure to high temp in early development (fever)
o Race/ethnicity (more common among whites)
o Low socio economic status
o Folate supplementation reduces the risk
Physiological changes in the mother’s body
Mother’s body
 Foetus = totally dependent on the mother’s nutrients received via:
 Sources: Amniotic fluid, the mother’s diet and nutrient stores and synthesis in the placenta
 Factors that influence the health of the mother: genetics, social factors, the environment, infection
Placenta
 New endocrine organ -connection between mother and infant
 Transfers nutrients
 Provides blood circulation from day 12
o Contact area of 13m2
o Maternal and infant blood never mix: separated by 2 layers
o Structure includes double lining of cells separating maternal and fetal blood
o Acts as barrier to some harmful compounds
o Nutrients transferred by different mechanisms
Mechanisms of nutrient transfer
 Passive diffusion
o AA, O2, CO2, free fatty acids, electrolytes, fat soluble vit’s, glucose, ketones, sodium, chloride
 Facilitated diffusion
o Monosaccharides (glucose), iron, vit A & D
 Active transport
o AA for transfer, Cations (Ca, Fe, K, Zn), I, P, water soluble vit’s
 Pinocytosis (endocytosis)
o Immunoglobulins (large protein)
o Albumin
o Nutrients and other molecules are engulfed by placenta membrane and released into fetal blood
supply

Mechanisms of nutrient transfer – prevents nutrients gliding back over concentration gradient
 Vitamin C- In foetus converted to a form that cannot cross back
 Ca - Protected by hormonal function
Placental quality influences foetal outcomes:
 Small placenta:
 Fewer cells
 Lower nutrient production & flow of nutrients
 Less inhibition of transfer of dangerous materials
 Prenatal nutrient deficiencies are incurable
 Birth weight: is the best single indicator of future health status
Respiratory & Excretory Functions
o Exchange gases
o Optimal O2 supply
o Hb production regulates O2 exchange
o Excretion of metabolic waste products (urea, creatinin, uric acid)
Regulatory Functions
 Hormones (30 hormones), include:
o Human chorionic gonadotropin (HCG)
 Implantation, oestrogen & progesterone production
...
Stimulates
growth of endometrium
...

o Oestrogen
 Facilitates implantation, ligament flexibility, breast duct development
...

Blood volume & composition
 Blood volume needs to increase
o During Tr1: 33% of blood increase
o 34weeks: 50% increase
 Limited increase: LBW, Stillbirth, S-Abortion
 Advantage: More blood circulation: carrying nutrients away
Cardiovascular & pulmonary system
 Heart rate increases > capacity to pump blood due to increased blood volume
 Increase of 02 need & decrease in CO2 limit – dyspnoea (shortness of breath)
 Foetal pressure increases the problem
GIT




Decrease in gastric motility & increase in intestinal tonus – hormonal onset
o Increases transit time, decreases amounts in transit & increased absorption
o Nausea (early)
o Constipation (later)
o Increased appetite
o Cravings
o Lowered salt threshold
Relaxed oesophageal sphincter – heartburn

Renal functions
 Kidneys work load increases
o Increase in blood volume
o Increased work load
o More nutrients could be lost
o Hold back more water : oedema
Hormonal changes
 Various hormones are secreted during pregnancy:
o Pregnancy hormones: Progesterone & oestrogens
o Aldosterone
o Growth hormone
o Thyroxin: Increase in iodine uptake through thyroid gland
o PTH (Parathormone): Controlling blood calcium
BMR
 Heart rate increases & kidney function increases
 Affecting BMR
Foetal Programming
 Nutrients influence growth & development of an infant
 Genetic research shows how it might influence future the infant’s development of obesity and diseases in
adulthood
...
it may even influence succeeding generations
Changes during Pregnancy: Nutritional Needs NB
Increase in Nutritional Needs
 Caused by:
o Alteration in body functions of mother & placenta
o Needed weight gain
o Growth of the infant
o Infant stores
 Needed for:
o Growth & physical activity of foetus (525kJ/day)
o Growth of placenta
o Normal increase in body size of mother
o Additional work load to carry weight of foetus and extra motherly tissue
o Slow but steady increase in BMR
o You require an additional 357000kj over 9 months = 1260kj/day + normal requirement
Nutritional Needs
 Pre- pregnancy and during pregnancy nutrition is very important (adequate energy & nutrients)
 A: Energy needs increase( especially during 2nd and 3rd trimester)
 B: Maternal weight also plays an NB role before and during pregnancy
 C: Also increased need for other essential nutrients
Early Deprivation of Nutrients
 Impair health of future generations
 Higher susceptibility to illness
 Higher risk of birth defects
 Higher risk of retarded mental and physical development
 Influence learning ability and behaviour

Maternal Weight before Pregnancy
 Underweight
o High risk of having a low birth weight
(LBW) infant
o Especially if malnourished or unable to
gain sufficient weight during pregnancy
o Preterm births and infant deaths are
higher in underweight women
 Overweight and obesity
o Low risk of LBW baby, however high risk
for post term births with large new-born
babies
o Increased risk of difficult labour
o Poor development of embryo higher in obese mothers
o Higher risk for neural tube defects
o Higher risk for giving birth to children with heart defects
Energy Requirements
 If she does not receive the required energy – the fat reserves would be too small to:
o Maintain normal lactation (breast feeding)
o Build energy reserves in times of need
 Foetus contains 0
...
g
...
72m tall
 BMI = 65 / (1
...
958

= 21
...
5 & 16kg throughout her pregnancy

Speed of weight gain
 Underweight mother = 400g/week
 Normal weight mother = 500g/week
 Overweight mother = 300g/week
Weight Loss after Pregnancy

Other Nutritional Demands of Pregnancy
 Energy
nutrients
and
vitamins
supporting
energy/protein metabolism are needed:
o Protein
o CHO
o Thiamin, riboflavin and niacin
o Vitamin B6
o Vit A & Fe: Needed to fill up babies stores
o Vit D, C & Ca: Only needed for foetal growth
while inside the mother
 Nutrients needed for cell growth and blood production:
Folate, Vitamin B12, Iron and Zinc
 Nutrients for bone development: Calcium, phosphorus, vitamin D, magnesium, vitamin C, vitamins A and E
and iodine
Protein Requirements
 Estimated 925g (3
...
7mg/day stored in last trimester
 3mg extra dietary Zn required above nRDA of 8mg = 11mg
 Low Zn = extended labour, malformations, LBW and hypertension
 >60mg / day Fe interferes with Zn absorption
Vitamin Requirements: Vitamin A
 Large intakes – causes birth defects
 750 µg/day in first trimester (needed to build up babies stores)
 Well-nourished moms = enough - preformed Vitamin A stores
 N RDA = 700µg/day
 P RDA = 770µg/day
Vitamin Requirements: Vitamin D
 Need 5µg/day = normal RDA
 Active role in Ca metabolism
 Overload – foetal hypercalcemia

Vitamin Requirements: Vitamin E
 No role in conception
 RDA = 15mg/day
 Balanced diet will provide enough
 Little transfer across placenta
 RDA stays the same as N
Vitamin Requirements: Vitamin K
 Prevents bleeding
 Supplement: Mom: Last few weeks of pregnancy
 Baby injected shortly after birth to prevent bleeding
 RDA = 90µg/day
Vitamin Requirements: Vitamin B
 B1 (Thiamine)
o NB – Relationship with energy
o More held back during pregnancy
o B1 Supplements help to alleviate nausea associated with pregnancy
o nRDA = 1
...
4 mg/day
 B2 (Riboflavin)
o Increased needs: Growth of foetus, growth of additional tissue and advise additional 0
...
1mg / day
o pRDA: 1
...
g
...
3mg / day
o pRDA: 1
...
4µg/day
o pRDA: 2
...
g
...
g
...
o
...
3% risk if 35yrs, 0
...

o Reason remains a mystery: Might be that the uterine blood flow of older women fail to adapt to the
increased demands of pregnancy
Adolescence
o
o
o

Closest to menarche - higher nutritional risk
Risks: Preeclampsia, anaemia, prematurity, stillbirths, LBW, infant mortality, complicated labour
Very high nutritional needs during pregnancy

Extreme weight
 Underweight (BMI<19
...

o Gestational diabetes - test at 24-28 weeks of gestation
o Risks for development if: Previous gestational diabetes, history of large infants (4 kg), a family history
of Diabetes Mellitus, Obesity or excessive weight gain, Age 30 or older or History of complications on
past pregnancies
 Hypertension
o Pre-existing HT
 Maternal complications: Heart attack / Stroke
 LBW, abrupt placenta ---> stillbirth
o Transient HT
o 2nd half gestation, usually mild (Differs from pre-eclampsia and eclampsia which are diseases)
o Pre-eclampsia
 Characterized by hypertension, oedema & proteinuria
 Oedema – differs from normal : whole body
 Primiparas (1st baby) after 20 weeks gestation
 Effects ---> foetal growth retardation, stillbirth
 Eclampsia: convulsive seizures & death
 Pre-eclampsia
o Characterised by:
 Oxidative stress, inflammation, and endothelial dysfunction
 Blood vessel spasms and constriction
 Increased blood pressure
 Adverse maternal immune system responses to the placenta
 Platelet aggregation and blood coagulation due to deficits in protacyclin relative to
thromboxane
 Alterations of hormonal and other systems related to blood volume and pressure control
 Alteration in calcium regulatory hormones
 Reduced calcium excretion

o



Symptoms
 Hypertension
 Sensitivity of the eyes to
 Increased urinary protein
bright light
(albumin)
 Blurred vision
 Decreased plasma volume
 Abdominal pain
expansion
 Nausea
 Low urine output
 Increased
platelet
 Persistent
and
severe
aggregation, vasoconstriction
headaches
Phenylketonuria (PKU)
o Inborn (inherited) error of metabolism
o Recessive gene
o Inability to digest phenylalanine found in artificial sugars (aspartame)
o Can lead to mental retardation
o Maternal PKU - spontaneous abortion, mental retardation, congenital heart disease or LBW

Practices of Concern
 Eating disorders: anorexia, bulimia, compulsive eating and strict vegetarians, low kilojoule and low CHO diets,
Pica, superstitions and non-prescribed vitamin/mineral supplementation
Alcohol use
Foetal alcohol syndrome (FAS)
 Irreversible mental and physical retardation, behavioural problems, unique physical traits, feeding problems
 Tobacco and drug use
 Abortions, SGA ( LBW), prematurity, high mortality, retarded development, impaired intellectual &
behavioural development, and complications at birth
 Environmental contaminants
o Lead poisoning – damage on foetus CNS
o Mercury – found in some fatty fish – CNS & Brain
o Avoid shark, swordfish, mackerel, tilefish – supplements of fish-oil NOT recommended
o Vitamin / mineral, Caffeine and weight-loss dieting



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