Lecture 6a: Maternal Nutrition Flashcards
What state is pregnancy?
an anabolic state - building
What alters nutrient metabolism in pregnant mothers?
Hormonal changes
What is a higher energy requirement in pregnant mothers needed to support?
- Fetal growth and development
- Reproductive tissue accretion
- Maternal homeostasis
What happens to basal energy expenditure during pregnancy?
Increases due to added metabolism of uterus and fetus and increased work of the maternal heart and lungs
What happens to thermic effect of food during pregnancy?
Remains unchanged
What happens to the cost of physical activity during pregnancy?
Energy cost remains the same
What is recommended energy intake during first trimester?
Extra energy not required
What is the recommended energy intake during second trimester?
1,400kJ/d (340kcal/day) added to EER of non-pregnant women
What is the recommended energy intake during third trimester?
1,900kJ/d (452kcal/d) added to EER of non-pregnant women
What are LCPUFA’s?
Long-chain polyunsaturated fatty acids
What are essential and used to make LCPUFA’s?
Linoleic (6) and a-linolenic acid (3)
What happens when we eat omega-6 and omega-3 fatty acids?
They go through cycles of desaturation and elongation
What is desaturation?
adding on double bonds
What is elongation?
adding 2 C atoms to carboxyl end of the chain
What do Omega-6 fatty acids (linoleic acid) end up as?
Arachidonic acid (AA) - one cycle
What do Omega-3 fatty acids (a-linolenic acid) end up as?
EPA and DHA
Why is more AA generated compared to EPA and DHA?
Omega 3 is more of a process, therefore less EPA and DHA are generated compared to AA
Why is there competition between substrates for n-3 and n-6 fatty acids?
Because chain elongation/saturation enzymes are shared between them
What is DHA a critical component of?
Cell membranes, especially in the brain and retina
What is AA a critical component of?
Both a membrane component and a precursor to potent signalling molecules, the prostaglandins and leukotrienes (mediate inflammatory responses)
What is fetal LCPUFA accumulation?
Fetus has active desaturases but limited ability to make LCPUFA’s so it is dependent on placental supply for both LCPUFAs and essential fatty acids - therefore accumulates over pregnancy
What is the cord blood concentration of LCPUFA’s influenced by?
Maternal diet
What happens to n-3 fatty acid deposition in brain and retina look like over pregnancy?
Occurs fairly slowly and then rapidly accumulates during the last trimester
What are sources of linoleic acid (n-6)?
Soybean, safflower, sunflower and corn oils; green leafy vegetables; nuts and seeds
What are sources of a-linolenic acid (n-3)?
Soybean, canola, flaxseed and walnut oils; nuts and seeds
What are sources of AA?
Egg yolk and meats (organ meats)
What are sources of EPA?
Fish oils, oily fish
What are sources of DHA?
Fish oils, oily fish
What is a rich supply of n-3 fatty acids during pregnancy associated with?
reduced incidence of low birth weight
What are LCPUFA’s (DHA and EPA) thought but not proved to do during pregnancy?
Improve cognition or development in children
What is monomethylmercury?
Occurs naturally in the environment and in industrial pollution accumulating in streams and seas
What is monomethylmercury taken up by?
Aquatic organisms and concentrated in fish
Where are higher concentrations of monomethylmercury found?
Longer living fish such as shark, ray, swordfish, gemfish, orange roughy
What percent of mercury from power plants ends up in fish?
40%
What is the concern over methylmercury?
It is a neurotoxin; large amounts can damage the developing nervous system of the fetus and delay mental development
What is the recommendation for fish and seafood in pregnant women?
Reduce mercury intake; eat long-living fish less than 3-4 times a week - fish from geothermal areas only once a week or fortnight
What is the most common micronutrient deficiency during pregnancy?
Iron
Requirements for absorbed iron increase slowly from ?? in the first trimester to ?? in the 3rd trimester
1.2mg/d to 5.6mg/d
Why do iron requirements increase during pregnancy?
- Pregnant women have more blood
- Growing fetus
- Blood loss during delivery
What is the RDI for pregnant women aged 14-50 years?
27mg/d (increased by 9mg)
What is the UL for iron in pregnant women?
45mg/d
What is peripartum?
occuring during the last month of gestation or first few months after delivery
Anemia has been associated with in increased risk of what for newborns?
- LBW
- SGA
- Preterm birth
- Decreased iron stores
- Impaired cognition
- Impaired growth
Anemia has been associated with in increased risk of what for mothers?
- Cardiac failure
- Death from peripartum hemorrhage
What percent of pregnant women have anaemia globally?
40%
Where is anemia in pregnant women the highest and lowest?
- Highest in SE Asia (58%)
- Lowest in Americas (25.5%)
What is the WHO global nutrition target for 2025 in women?
a 50% reduction in anemia among women
What are the iron supplementations for pregnant women from WHO?
60mg daily for pregnant women living in areas where malnutrition is prevalent
When does WHO recommend iron supplementation?
Taken as early as possible and throughout pregnancy
What are women taking iron supplements less likely to have?
LBW babies and mean BW was higher than controls
What does iron supplementation NOT have an effect on?
Preterm birth or neonatal death
What is the screening procedure for iron status in NZ?
Iron status is taken at 20 weeks and at 26-28wks gestation
What procedures are taken to establish iron status?
Complete blood count (CBC), serum ferritin, hemoglobin (Hb)
What does HB <100 at booking indicate?
Urgent indication to start oral supplementation and consideration of parental (IV) iron
Why should serum ferritin be taken?
To establish the diagnosis of iron deficiency (especially before parenteral iron)
What Hb indicates severe anemia?
<89g/L
What happens at the first visit <20 weeks for iron status?
- Request complete blood count and ferritin
- Encourage iron rich diet
- Provide blood form for repeat blood tests at 26-28wks
What happens at the second visit at 26-28wks for iron status?
- Request complete blood count and ferritin
- Continue iron rich diet
What are the side effects of iron medications?
- Nausea
- Vomiting
- Constipation
- Diarrhoea
- Dark coloured stools
- Abdominal distress
How should iron medications be taken?
- Start with half the dose and gradually increase to the full dose
- Divided doses with food
- Coated or delayed-release may have fewer side effects; but less absorption
What are the two forms of supplemental iron?
Ferrous and ferric
What form of supplemental iron is the best abosorbed?
Ferrous iron salts
What is elemental iron?
The amount of iron available for absorption
What is prophylatic iron supplementation?
routine administration of iron supplements to pregnant women to prevent iron deficiency and iron-deficiency anemia
What are the risks of prophylatic iron supplementation?
- Increased risk of gestational diabetes
- Increased oxidative stress
What are interventions aimed at preventing iron deficiency?
- Food-based
- Supplementation
- Fortification
What is delayed ‘optimal’ cord clamping?
Changing from immediately after to 1-3 minutes after delivery to clamp cord
What happens during delayed cord clamping?
Transfer from the placenta about 80ml at 1 min to about 100ml at 3 minutes of blood
What are the benefits of delayed cord clamping?
Addititonal volumes can supply extra iron of 40-50mg/kg of body weight
