Nutrition and Physiology in Pregnancy

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Questions and Answers

What is the effect of increased oxidation and free radical formation during pregnancy?

It results in increased antioxidant absorption.

It overwhelms the body's protective mechanisms. (correct)

It is associated with inflammation and tissue repair.

It leads to a decrease in energy production.

What is the preferred fuel source for the fetus during pregnancy?

Proteins

Vitamins

Carbohydrates (correct)

Fats

How does maternal insulin resistance affect glucose metabolism in the third trimester?

It lowers the body's capability to utilize glucose. (correct)

It decreases the mother's reliance on fat.

It increases glucose conversion to glycogen.

It elevates fasting maternal blood glucose levels.

What is the primary reason for increased blood lipid levels during pregnancy?

Fat stores accumulation and mobilization. Signup and view all the answers

During which trimester does the body primarily rely on fats for energy due to insulin resistance?

Third trimester Signup and view all the answers

What impact does adequate intake of Vitamins C and E have during pregnancy?

It strengthens the mother's body against oxidative damage. Signup and view all the answers

What is the total amount of protein that accumulates during pregnancy?

925 g Signup and view all the answers

What physiological change occurs in blood lipid profiles by the third trimester?

Atherogenic lipid profile. Signup and view all the answers

What is one of the main functions of the placenta?

Hormone and enzyme production Signup and view all the answers

Which of the following substances can pass through the placenta?

Certain viruses Signup and view all the answers

How does the placenta prioritize nutrient use during low supply?

Maternal needs first, then placenta, then fetus Signup and view all the answers

Which factor does NOT influence nutrient transfer through the placenta?

Maternal weight Signup and view all the answers

During what stage do cells acquire characteristics different from their original form?

Differentiation process Signup and view all the answers

What is the desirable birthweight range for newborns to reduce the risk of developing diseases?

3500-4500 g Signup and view all the answers

During what weeks of pregnancy do maternal anabolic changes occur?

Weeks 1-20 Signup and view all the answers

What percentage of fetal growth occurs during the maternal catabolic changes phase?

90% Signup and view all the answers

What is the average length of a pregnancy measured from conception?

38 weeks Signup and view all the answers

Which of the following statements accurately describes the placenta?

It facilitates nutrient and gas exchange between mother and fetus. Signup and view all the answers

What is the average pregnancy duration measured from the onset of the last menstrual period?

40 weeks Signup and view all the answers

What is the primary cause of edema during pregnancy?

Accumulation of extracellular fluid Signup and view all the answers

How much does body water change during pregnancy?

Increases from ~7 L to 10 L Signup and view all the answers

What is the recommended adequate intake (AI) of EPA and DHA during pregnancy?

300 mg Signup and view all the answers

What can excessive intake of retinoic acid during pregnancy lead to?

Fetal malformations Signup and view all the answers

How much calcium is recommended during late pregnancy?

300 mg Signup and view all the answers

What is the consequence of iron deficiency anemia in pregnant women?

Lower birth weight Signup and view all the answers

What is the maximum daily intake of vitamin D recommended during pregnancy?

50 mcg Signup and view all the answers

What are critical periods in embryonic and fetal development?

Time frames when specific organs are formed and integrated. Signup and view all the answers

Which of the following is the main fetal growth stimulator?

Insulin-like growth factor (IGF-1) Signup and view all the answers

What characterizes a newborn classified as dSGA?

Weight is less than the 10th percentile but normal head circumference. Signup and view all the answers

Which factor can lead to decreased levels of IGF-1 in fetal growth?

Maternal under nutrition Signup and view all the answers

What does pSGA indicate about a newborn's growth pattern?

They experience long-term malnutrition. Signup and view all the answers

Which statement about the stages of growth and development is accurate?

Maturation stabilizes cell number and size. Signup and view all the answers

Which of the following factors is linked to variations in fetal growth?

Genetically programmed growth Signup and view all the answers

What is a characteristic feature of dSGA infants immediately after birth?

Skinny appearance with a small abdominal circumference. Signup and view all the answers

What is the primary benefit of antioxidants from plants during pregnancy?

Protection of fetal DNA Signup and view all the answers

What dietary source is highly recommended for iodine intake during pregnancy?

Fish and shellfish Signup and view all the answers

What is the recommended frequency and duration of exercise for healthy pregnant women?

3-5 times a week for 30 minutes Signup and view all the answers

Which of the following statements about caffeine intake during pregnancy is true?

High levels above 500 mg/day can relate to miscarriage. Signup and view all the answers

What condition can result from low zinc intake during pregnancy?

Growth impairment and mental retardation Signup and view all the answers

Study Notes

Nutrition During Pregnancy

Time-related terms:
- Periconceptional period: Time before conception
- Trimester 1: Weeks -4 to 12
- Trimester 2: Weeks 13-28
- Trimester 3: Weeks 29-40
- Preterm: <37 weeks
- Postterm: >42 weeks
- Term: 38-42 weeks
- Perinatal: 20 to 24 weeks gestation to 7 to 28 days after birth
- Conception: Fertilization
- Embryo: Early stage of development
- Fetus: Later stage of development
- Miscarriage/ Spontaneous abortion: Loss of pregnancy before 20 weeks
- Fetal death/Stillbirth: Death of a fetus after 20 weeks
- Neonatal/Newborn/neonate: First 28 days of life
- Postneonatal: After 28 days of life
- LMP: Last menstrual period
Infant Mortality and Low Birthweight:
- Low birthweight (LBW) and preterm infants are at high risk of death in the first year of life.
- 8.2% of births are LBW, but comprise 66% of infant deaths.
- 12.7% are born preterm with high infant mortality.
- Shorter pregnancies result in lower birth weights.
Reducing Infant Mortality and Morbidity:
- Desirable birthweight is 3500-4500 g (7 lb 12 oz to 10 lb).
- Infants born with desirable weight are less likely to develop heart and lung diseases, diabetes, and hypertension.

Physiology of Pregnancy

Gestational age: Assessed from the date of conception; Average pregnancy is 38 weeks
Menstrual age: Assessed from the onset of the last menstrual period; Average pregnancy is 40 weeks

Maternal Physiology

Changes in maternal body composition and functions occur in a specific sequence.
Maternal plasma volume increases first.
Maternal nutrient stores accumulate next.
Placental growth precedes fetal weight gain.

Placenta

Disk-shaped organ for nutrient and gas exchange between mother and fetus.
At term, the placenta weighs about 15% of the fetal weight.

Normal Physiological Changes During Pregnancy

Two phases of changes:
- Anabolic: Build mother's capacity to deliver nutrients to the fetus (1-20 weeks). ~10% of fetal growth occurs.
- Catabolic: Nutrients delivered to the fetus (20 weeks - delivery) ~90%of fetal growth occurs in this stage.

Body Water Changes

Increases from ~7L to 10L due to increased plasma and extracellular volume and amniotic fluid.
Two-thirds of the expansion is intracellular (blood and body tissues), and one-third is extracellular (fluid between cells).
The increase starts a few weeks after conception and peaks at 34 weeks.
Early pregnancy surges in plasma volume cause fatigue and swelling.
Healthy plasma volume expansion, if not accompanied by hypertension, and strongly related to birth weight.

Maternal Nutrient Metabolism

Pregnancy is a pro-oxidative state.
Increased oxidation and free radical formation results from increased energy production in placental and maternal mitochondria, insulin resistance, diabetes, preeclampsia, obesity and infections.
Excess iron supplementation may also contribute to increased oxidation.

Pregnancy: A Pro-Oxidative State

Oxidative damage to maternal and fetal cells occurs when the body's protective mechanisms are overwhelmed or when external antioxidant supplies are low.

Adequate intake of Vitamins C and E is important.
Wide variety of naturally occurring antioxidants in vegetables and fruits.

Carbohydrate Metabolism

Glucose is the preferred fuel for the fetus.
"Diabetogenic effect of pregnancy" due to maternal insulin resistance in the third trimester.
First half: High estrogen and progesterone stimulate insulin, increasing glucose to glycogen and fat.
Second half: Human placental lactogen (hCS) and prolactin inhibit glucose conversion to glycogen and increase reliance on fat for energy.
Fasting maternal blood glucose levels decline in the third trimester, due to increased utilization by the fetus.
Postmeal blood glucose levels are elevated and higher than before pregnancy.

Protein Metabolism

About 925 g (2 pounds) of protein accumulates during pregnancy.
Protein and amino acids are conserved during pregnancy.
Reduced levels of nitrogen excretion.
Maternal and fetal needs for protein are fulfilled via the mother's dietary protein intake.

Fat Metabolism

Fat stores accumulate in the first half with enhanced fat mobilization in the second half of pregnancy.
Blood lipid levels increase dramatically.
Increased cholesterol is used as a substrate for steroid hormone synthesis in the placenta.
Fats are crucial for fetal nerve and cell membrane formation.
Small increase in pregnant HDL declines within a year postpartum, associated with higher risk of heart disease.
Most women have an atherogenic lipid profile by the third trimester.

The Placenta

Functions:
- Hormone and enzyme production
- Nutrient and gas exchange
- Waste removal from fetus
Structure: Double lining of cells separating maternal and fetal blood.
Role: Acts as a fence, rather than a filter. Potentially harmful substances (alcohol, high vitamins, certain drugs, and viruses) can pass, as well as certain maternal blood components (RBC) and bacteria.

Nutrient Transfer

Placenta uses 30-40% of glucose delivered to fetus.
If nutrient supply is low, placenta takes priority.
Factors affect transfer: Molecule size and charge, lipid solubility, and nutrient concentration in maternal and fetal blood.

The Fetus and a Parasite

Nutrients are first used for maternal needs, then the placenta, and lastly for the fetus.
Underweight women gaining the same weight as normal weight women tend to deliver smaller babies.
Fetal growth tends to be reduced in pregnant teens who gain height during pregnancy.

Critical Periods of Growth and Development

Differentiation: Cellular acquisition of functions different from the original cells. Happens over time intervals.
Critical periods: Preprogrammed embryonal and fetal periods when specific cells, organs, and tissues form and integrate or establish function. Most intense in the first two months after conception.
Four periods of growth and development: Hyperplasia(↑ cell multiplication), Hyperplasia & hypertrophy, Hypertrophy(↑ cell growth), Maturation (stabilization of cell number & size).

Variation in Fetal Growth

Linked to energy, nutrient, and oxygen availability and genetically programmed growth/development.
Insulin-like growth factor (IGF-1) is the main fetal growth stimulator.
Maternal nutrition sensitively influences IGF-1 levels.

Newborn Weight Classifications

SGA (small for gestational age): Weight less than the 10th percentile for gestational age. Further divided into dSGA and PSGA classifications.
dSGA (disproportionately small for gestational age): Weight is less than 10th percentile with normal length and head circumference. Looks skinny and wasted, and lacks glycogen in the liver and body fat.
PSGA (proportionately small for gestational age): Weight, length, and head circumference are less than the 10th percentile, likely due to long-term malnutrition.
LGA (large for gestational age): Weight is more than the 90th percentile for gestational age. Weight over 4500g. Often linked to pregnancy obesity or poorly controlled diabetes.

Preterm Delivery

Infants born prematurely are at risk for death, neurologic problems, congenital malformations, low IQ scores, and chronic health problems such as cerebral palsy.
Characterized by impaired muscle activity and coordination at birth.
Complications include growth, digestion and respiratory problems.
Premature infants are immature.

Fetal-Origins Hypothesis of Later Disease Risk

Exposer to adverse factors during critical developmental periods can have permanent effects on body structures and functions.
Exposures may increase susceptibility to CVD, type 2 diabetes, hypertension, and other diseases in adulthood. (Fetal Programming)

The Fetal-Origins Hypothesis: Mechanisms

Nutrition programming: Fetal exposure to specific energy and nutrient levels modifies gene function affecting metabolism.

Pregnancy Weight Gain Recommendations

Underweight, normal weight, overweight, obese individuals have different recommendations for weight gain during pregnancy.
Twins have higher recommended weight gain than single pregnancies.

Composition of Weight Gain

Table demonstrating the components of weight gain over time during pregnancy, including fetus, placenta, uterus, amniotic fluid, breasts, blood supply, and maternal stores.

Postpartum Weight Retention

Concerns exist over long-term obesity after pregnancy.
Women lose approximately 15 pounds at delivery.
Weight loss is difficult for some individuals due to high weight gain during pregnancy.
Lactation women lose slightly more weight.

Energy Requirements in Pregnancy

~300 additional calories per day (increased during 2nd & 3rd trimester).
Total calories consumed over pregnancy: ~80,000 kcal.
Assessment of caloric intake based on body weight.

Carbohydrate Intake During Pregnancy

Carbohydrate intake recommended (50-65% of total calories).
About 175 g of carbohydrate is recommended.
High fiber foods for phytochemicals and against constipation are recommended.
Glycemic index (GI) of carbohydrates (high-GI foods increase fetal fat).

Artificial Sweeteners

No scientific evidence of harm.
Includes aspartame and acesulfame K.

Alcohol Ingestion

Strongly discouraged during pregnancy.
Crosses the placenta and disrupts normal growth and development.
Linked to abnormal growth and mental development in offspring (Fetal Alcohol Syndrome).

Protein Intake

Recommended protein intake is about +25 g/day for all females age 14+.

Maternal Intake of Omega-3 Fatty Acids

Adequate EPA & DHA intake during pregnancy and lactation linked to higher intelligence, better vision, and more mature CNS.
Dietary intake recommendations: AI = 300 mg, UL = 2 g

Vitamin A and Pregnancy Outcome

Important during cell differentiation, but excessive retonic acid (not beta-carotene) is harmful.
Vitamin A is necessary for development of organs, but excess amounts are harmful.
Excessive Vitamin A doses (not beta-carotene) are associated with fetal abnormalities (eg: small ears, brain malformations, heart defects).

Vitamin D Requirements

Poor fetal bone formation and calcium utilization.
Vitamin D deficiency can lead to small, poorly calcified bones and enamel, and low blood calcium after birth.
Dietary Vit D recommendations: 5 mcg or 200 IU in supplements.
Sun exposure for Vit D production is 2-3 times a week for 15 min (1250mcg).
Dark skin requires more sun exposure.
Dietary Vitamin D intake should not exceed 50 mcg/day.

Calcium Requirements in Pregnancy

Calcium absorption increases, especially in late pregnancy.
Deficiency in pregnant women can be associated with high blood pressure.
Deficiency is linked to bone demineralization.

Iron Requirements During Pregnancy

Need for iron increases to support fetal and placental development, as well as increased RBC production in the mother.
Iron deficiency in pregnancy is associated with preterm delivery.
Low scores on cognitive, language, and motor tests in infants born of mothers with iron deficiency anemia.

Zinc Requirements in Pregnancy

Zinc is crucial for protein synthesis, and has a high bioavailability in meat, and low in plant foods/cereals.
Zinc (30mg/day) and Iron (30mg/day)
Important for normal pregnancy outcomes.

Antioxidants from Plants

Antioxidants help protect fetal DNA.
Maternal vitamin E intake can reduce the risk of childhood asthma.

Iodine and Pregnancy

Iodine is essential for the synthesis of thyroid hormones and protein synthesis.
Deficiency early in pregnancy can cause hypothyroidism.
Deficiencies can lead to growth impairment, mental retardation, and deafness.
Dietary recommendations should include fish, shell fish, and seaweed.

Sodium During Pregnancy

No need for sodium restrictions in normal pregnancies for edema or high blood pressure management.

Caffeine Use in Pregnancy

No significant long-term effects on children from moderate coffee intake during pregnancy.
High caffeine consumption (> 500 mg/day) may be associated with pregnancy loss.

Exercise and Pregnancy Outcome

Moderate to vigorous exercise is safe for healthy pregnant women.
Recommendation: 3-5 times per week, 30 minutes at 60-70% VO2 max.

Common Health Problems During Pregnancy

Nausea/vomiting: Hyperemesis gravidarum. Management: Dietary supplements, Vitamin B6, multivitamins, ginger.
Heartburn: Management of heart burn is suggested.
Constipation: Management of constipation during pregnancy is suggested.

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Description

This quiz explores key concepts related to nutrition and physiological changes during pregnancy. It covers topics such as oxidation, fuel sources for the fetus, maternal insulin resistance, and the role of the placenta. Test your knowledge on how these factors contribute to maternal and fetal health.