6) Fat, Carbohydrate, Water, Mineral, Electrolyte, and Vitamin Requirements in Pregnancy Flashcards
How does BMR vary during pregnancy?
Increase
What two factors explain for the increase in BMR during pregnancy?
1) Metabolic contributions of the uterus and fetus
2) Increase in work of the lungs and heart
What is the strongest predictor of BMR? Why?
- Fat-free mass (FFM)
- Because fat mass is not metabolically active
What are the three components of FFM in pregnancy?
1) An increase in blood volume
2) Skeletal muscle mass
3) Fetal and uterine tissues
Which component of FFM
during pregnancy is low energy-requiring?
An increase in blood volume
Which component of FFM
during pregnancy is moderate energy-requiring?
Skeletal muscle mass
Which component of FFM
during pregnancy is high energy-requiring?
Fetal and uterine tissue
By late pregnancy, half of the increment of energy expenditure can be attributed to ________.
the fetus
What are the two additional energy requirements for pregnancy?
1) Energy required to provide for the growth of tissues
2) Energy required for the maintenance of new tissues
How may the energy cost of new tissue deposition be calculated during pregnancy?
- From the amount of protein and fat deposited throughout the pregnancy
- The quantity of protein and fat gained are converted to calories
- The total number of kilocalories gained during pregnancy is divided by the duration of pregnancy
Why is there an increase in the requirement of energy per gram to synthesize protein and fat?
The synthesis of protein and fat requires the addition of energy
How does PAL vary during pregnancy?
Decrease
How does TEE vary during pregnancy?
Increase
What is the median increase of TEE per gestational week?
8 kilocalories
The EER during pregnancy is the sum of which three components?
1) TEE of the woman in a non-pregnant state
2) Median change in TEE of 8 kcals/week
3) Energy deposition of 180 kcals/day
What is the additional energy requirement, in calories, during the first trimester?
- There is little weight gain and variation in TEE
- There is no additional energy required
What is the additional energy requirement, in calories, during the second trimester?
340 kilocalories
What is the additional energy requirement, in calories, during the third trimester?
452 kilocalories
What weeks does the first trimester correspond to?
Weeks 1 to 12
What weeks does the second trimester correspond to?
Weeks 13 to 27
What weeks does the third trimester correspond to?
Week 28 to birth
Which week is used for the multiplication of the TEE during the SECOND trimester to derive the additional energy requirements?
- Week 20 (midpoint of the second trimester)
- 8 kilocalories x 20 weeks
Which week is used for the multiplication of the TEE during the THIRD trimester to derive the additional energy requirements?
- Week 34 (midpoint of the third trimester)
- 8 kilocalories x 34 weeks
What two factors are the basis of the additional protein requirements during pregnancy?
1) The support in growth of maternal and fetal tissues
2) Maintenance of additional protein stores
Why do protein requirements vary with each trimester?
Due to differences in protein needs for growth and maintenance of the additional protein accretion that has accumulated by the end of each trimester
What is the estimate of protein requirements during pregnancy based on?
Growth and body composition at the end of each trimester
What is the additional protein requirement during the first trimester?
- There is low deposition of tissue during the first trimester
- There is NO increase in protein requirement
What is the additional protein requirement during the second and third trimesters? How is it determined?
- EAR: 21 grams of protein per day
- RDA: 25 grams of protein per day
- The additional pregnancy protein requirement during the second and third trimesters are averaged to devise the EAR
How is protein and energy related to low-birth weight infants?
Improving protein and energy nutrition during gestation, and prior to gestation, decreases the risk of low-birth weight infants
Where may omega-6 and omega-3 fatty acids be acquired to become incorporated into placental and fetal tissue?
Obtained from maternal tissues or through dietary intake
How does the AI for omega-6 fatty acids vary during pregnancy?
Increase (12 g/d to 13 g/d)
How does the AI for omega-3 fatty acids vary during pregnancy?
Increase (1.1 g/d to 1.4 g/d)
Which fatty acid is contained in high quantity in maternal and fetal blood of low-birth weight infants? What type of fatty acid is it?
ETA (omega-9)
Which fatty acids are contained in low quantity in maternal and fetal blood of low-birth weight infants? What type of fatty acid are they?
- AA (omega-6)
- DHA (omega-3)
What do high levels of ETA indicate? Why?
- Essential fatty acid deficiency
- If there is a lack of both omega-6 and omega-3 fatty acids, desaturase enzymes produce omega-9 fatty acids (such as ETA) from oleic acid
How is the ratio of omega-6 to omega-3 fatty acids altered by vegetarian diets? What is an adequate ratio?
- Vegetarian: 15:1 or 20:1 (HIGH)
- Mediterranean diet: 4:1 to 10:1 (LOW)
How may vegetarian diets pose risk for the brain development of the fetus?
Vegetarians have higher quantities of AA and lower amounts of DHA
How does metabolic rate vary during pregnancy?
Increase
What four factors cause an increase in metabolic rate during pregnancy?
1) Establishment of the placental-fetal unit
2) Increase in the energy supply for the growth and development of the fetus
3) Increased maternal storage of fat EARLY in pregnancy
4) Energy to sustain the growth of the fetus during the last trimester
What are three adaptations to pregnancy in terms of carbohydrate metabolism?
1) Decrease in fasting maternal blood glucose
2) Development of insulin resistance
3) Tendency to develop ketosis
Why is there an increase in glucose uptake during the second half of pregnancy?
Due to an upregulation of glucose transporters on the fetal portion of the placenta
What is the respiratory quotient (RQ)?
The ratio of CO2 produced by oxygen consumed
How does the RQ vary during pregnancy?
Increases for both BMR and the total 24-hour energy expenditure
How does glucose utilization by the maternal-fetal unit vary during pregnancy?
Increase
What percentage does glucose oxidation account for in the estimated fetal brain’s fuel requirement? What does that indicate?
- 70%
- Indicates that the fetal brain can use keto acids
How does keto acid concentration vary during pregnancy?
Increase
What is the glucose requirement during late gestation? How does that compare to the maternal-fetal glucose transfer rate?
- Glucose requirement is 33 g/d
- Maternal-fetal glucose transfer rate is lower, averaging at 22 g/d
What quantity of glucose transferred from the mother does the fetus utilize?
- Essentially, all of the glucose transferred from the mother
- Glucose transfer rate: 22 g/d
- Fetal brain glucose utilization rate: 23 g/d
What is the carbohydrate requirement during pregnancy based on?
The transfer of an adequate supply of glucose to the fetal brain that is independent of the utilization of keto acids
What is the additional carbohydrate requirement during pregnancy?
35 g/d
What is the coefficient of variation for carbohydrates during pregnancy based on?
Variations in brain glucose requirement
How does the recommendation for fiber vary during pregnancy?
- There is NO variation (AI = 14 grams/1000 kilocalories)
- There is no evidence that the beneficial effect of fiber for pregnant women is different than for non-pregnant women
How does the recommendation for water vary during pregnancy?
The AI increases from 2.7 L/d to 3.0 L/d