Maternal Nutrition Flashcards
What does preconceptual mean?
1-3 months prior to conception
What does periconceptual mean?
Immediately prior to conception and early gestational phase
What is the first trimester?
0-13 weeks (most crucial for baby’s development)
What is the second trimester?
14-26 weeks
What is the third trimester?
27-40 weeks
What does preconceptual nutritional status influence?
Birth outcomes
Why does mother need to be at optimal nutritional status during the embryonic stage of fetal growth (weeks 2-8) and what is the problem with this?
- Nutrients primarily from maternal blood
- Critical period of development
- Often before the pregnancy is confirmed - 50% pregnancies are ‘unplanned’ so women may not be nutritionally ready for pregnancy
- Lack of certain nutrients may cause specific congenital abnormalities
Why is maternal nutrition important throughout pregnancy?
1) During pregnancy the maternal diet must provide sufficient nutrients to meet the mother’s usual requirements as well as those of the growing fetus and stores for use during the third trimester and lactation
2) Nutritional requirements during pregnancy to support fetal growth and development and expanding maternal tissues (incl. preparation for lactation)
3) > 90% fetal growth during 2nd half of pregnancy - nutrients stored in early pregnancy in preparation for rapid growth
4) Fetal nutrition in utero has a key role in the health of the newborn infant and throughout the lifecycle
What is the normal weight gain in pregnancy for a mother who is normal weight when they conceive?
12kg (mean weight gain in pregnancy) - but variation and SD is huge
What causes the weight gain in pregnancy?
1) Fetus
2) Placenta and amniotic fluid - variable depending on size of mother
3) Uterus and breasts - variable depending on size of mother
4) Blood
5) Extracellular fluid
6) Maternal fat stores - v variable
What is the consequence of inadequate gestational weight gain (GWG)?
Low birth weight
What are the consequences of excessive GWG?
1) Adverse maternal and neonatal outcomes
2) Postpartum weight retention - pregnancy can result in obesity of the mother
What guidelines are used for GWG recommendations?
- No UK evidence based GWG recommendations - use American guidelines
- IOM weight gain targets depending on BMI
- However not realistic for obese women
- Good to advise underweight women to put on weight
- Recommending to lose weight can lead to still birth (ketones)
When should how much weight be gained in pregnancy?
Normally 0.5-2kg of weight is gained during the first trimester of pregnancy and the remainder of the recommended weight gain is expected during the second and third trimesters
What are the risks associated with maternal obesity?
1) Gestational diabetes
2) Pre-eclampsia
3) Thromboembolism
4) C section
5) Stillbirth
6) Congenital malformation
7) Miscarriage
8) Haemorrhage
9) Infection
What is the mean optimal birth weight?
3.3kg
Is it necessary to eat for two in pregnancy?
- No - unless underweight
- Should only eat an additional 191 kcal/day in third trimester
- Also have reduced physical activity
- Weight loss not advised
Why is the neural tube vulnerable to preconceptual nutritional deficiencies?
Bc closure of the neural tube occurs very early in pregnancy (12 weeks)
What are the oral folate supplement recommendations in early pregnancy?
1) All women planning pregnancy should take 400 micrograms per day 8 (3) weeks pre-conception until 12 weeks post conceptually (need 20x more folic acid in first trimester/pre-conception) - if taking 5mg can mask B12 deficiency
2) If have had a child with a prior NTD, they should supplement 5mg of folic acid per day (if higher risk of NTDs)
What is folic acid critical for?
- It is critical in early pregnancy to protect against NTDs in the development fetus - should consume folic acid 8 weeks prior to conception
- It also prevents megaloblastic anaemia in later pregnancy
What are the oral folate diet recommendations?
Choose foods fortified with folic acid (some breakfast cereals) and folate-rich foods e.g. dark green leafy vegetables
What are the oral folate recommendations for pregnancy after 12 weeks?
For the remainder of pregnancy, RNI = non-pregnant (200) + 100 micrograms/day to prevent megaloblastic anaemia
What are the vitamin A recommendations in pregnancy?
- Increased requirements - RNI = 600 + 100 retinol equivalents (RE)/day
- RNI of 600 for women aged 16-55 so in pregnancy only need another 100 RE (unit for vitamin A)
- But high intakes are teratogenic in the preconceptual period
What are high intakes of retinol > 3000 RE/day in first trimester associated with?
An increased risk of malformations
What vitamin A rich foods should be avoided in pregnancy?
- Liver and liver products (pate)
- Supplements containing vitamin A and fish liver oil supplements (retinol form, can’t stop absorption so can get too much)
What are good dietary sources of vitamin A that are suitable during pregnancy?
1) Milk/milk products
2) Eggs
3) Leafy greens
4) Carrots - if too much retinol, body stops conversion from beta carotene
What is vitamin D deficiency in pregnancy associated with?
1) Congenital rickets in the newborn
2) Impaired fetal/infant skeletal growth in the absence of rickets
What is the vitamin D supplement recommendations in pregnancy?
10 micrograms/day of vitamin D supplement when pregnant and breastfeeding (esp. ‘at risk’ groups)
Describe vitamin D requirements and status in the UK
- Vitamin D requirements primarily met via sun exposure - depends on latitude in UK (only in summer) - won’t make vitamin D in UK in winter due to latitude of sun
- Low vitamin D status prevalent in the UK - USA put vitamin D in milk, we don’t
- Average intake is very low in young women - 2-3 micrograms/day
What groups are at risk of vitamin D deficiency?
- Compromised sunlight exposure
- Low vitamin D intake
- Pre-pregnancy BMI > 30
Why is calcium required in pregnancy?
For calcification of the fetal skeleton
What are maternal adaptations to meet calcium requirements?
1) Increased intestinal absorption of dietary calcium
2) Increased reabsorption of calcium by kidneys - enhanced retention
3) Increased bone turnover to release calcium
What is the recommendation for calcium supplement in pregnancy?
- No additional increment for pregnancy - RNI = 700 mg/day (19-50y), 800mg/day (15-18y)
- At risk’ subgroups may benefit from dietary advice e.g. adolescent mothers (bones developing), those who avoid dairy products, asian women (low vitamin D status)
How do iron requirements change through pregnancy and why?
- Requirements increase as pregnancy progresses
- Majority of iron is accumulated by the fetus in the 3rd trimester
- Full term baby is born iron replete (have enough iron to sustain them for the first 6 months of life - breast milk is relatively low in iron)
What are the maternal metabolic adaptations to meet the increased iron requirement?
1) Amenorrhoea
2) Increased absorption of dietary non-hem Fe
3) Mobilisation of maternal stores
Why is there a risk of iron deficiency anaemia in mothers with low iron stores?
Fetus acts as ‘parasite’ drawing on maternal stores
What are causes of infant iron deficiency anaemia?
- Rarely due to maternal iron deficiency anaemia
- Most commonly due to short gestation (pre term birth) bc babies haven’t been able to maximise on their iron stores
- Rare in full term
What are the iron supplement recommendations in pregnancy if someone has adequate iron stores at the start of pregnancy?
No additional increment
What are the iron supplement recommendations in pregnancy if someone enters pregnancy with low iron stores?
- There is an increased risk of preterm delivery so consider Fe supplement if Hb < 110 g/L (1st trimester) or 105 g/L (2nd trimester)
- Low iron can result in increased risk of maternal infection so want to focus on iron rich foods instead of supplementing
What are 10 tips for maternal nutrition?
1) Take a daily supplement - 10 micrograms/day of vitamin D throughout pregnancy and 400 micrograms folic acid until at least 12th week of pregnancy (can continue after)
2) Keep physically active
3) A healthy weight gain
4) Choose nutritious foods, not extra foods
5) Balance your diet
6) Eat fish twice a week
7) Choose nutritious snacks
8) Have 1.5-2L (6-8 drinks) per day for good hydration and limit caffeine to 200mg per day
9) Food safety
10) Avoid smoking and limit alcohol intake
How do you keep food safety in pregnancy?
- Throughly cook meat, fish and eggs
- Wash all soil from vegetables and fruit
- Avoid vitamins A supplements, liver, liver pate, unpasteurised dairy products, soft and blue cheeses, swordfish, marlin and shark
- Limit tinned tuna to 4 small servings per week (mercury builds up food chain)
What can you eat in pregnancy?
1) Cooked shellfish (prawns part of hot meal and cooked thoroughly), live or bio yogurt (if in UK - pasteurised), probiotic drinks, fromage frais, creme fraiche, sour cream, spicy food
2) Mayonnaise, ice cream, and salad dressing made with pasteurised egg - home made versions may contain raw eggs and must be avoided
3) Honey may be eaten during pregnancy but is not suitable for infants < 12 months
4) Pasteurised cheese including - hard cheese (cheddar and parmesan), feta, ricotta, mascarpone, cream cheese, mozzarella, cottage cheese, paneer, halloumi, processed cheese (cheese spreads)
What is general advice in pregnancy?
1) Alcohol - avoid if possible - max 1-2 UK units 1-2x/week
2) Exercise and sex - yes (moderate) - watch injuries with certain sports incl. cycling
3) Food-acquired infections - listeria and salmonella
4) Medicines - cautious - benefits might outweigh risk
5) Nutritional supplements 0 folate pre-conception, no routine iron, vitamin D (10 micrograms/day)
6) Don’t smoke (but smoking reduces chance of PE) or use cannabis
7) Work, put your seatbelt UNDER the bump, be DVT-aware when travelling (getting up, socks)
Why do we not focus so much on the weight of the mother?
Bc it is very variable
Is there a risk of folic acid excess?
Yes (but should still put folate in flour to decrease incidence of NTDs)
What puts someone at a higher risk of having a baby with an NTD and should therefore take 5mg of folate?
1) Maternal or paternal NTD
2) Previous pregnancy affected by NTD
3) Family history of NTDs
4) Pre-existing diabetes - not everyone takes it
5) Anti-epileptic medication
6) BMI > 30
What mutation may cause someone to be more at risk of having a baby with an NTD?
Mutations of 5,10-methylenetetrahydrofolate reductase gene
What may cause NTDs to arise/how does folic acid prevent them?
1) Mutations of 5,10-methylenetetrahydrofolate reductase gene
2) Differential methylation of IGF-2 (insulin-like growth factor) gene
3) Hyperhomocysteinaemia
4) Direct effect on neural epithelium in the embryo
What should the health check at the start of pregnancy consist of?
1) Weight - ideal weight
2) Pap smears up to date
3) Pre-existing medical conditions
4) Alcohol - what is normal
5) Smoking - advice smoking cessation
What % of pregnancies are unplanned?
40%
