Nutrition Module 12 Textbook Notes PDF

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Dr. Melanie Rozwadowski...

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Nutrition 120 Module 12: Maternal and Early Lifecycle Nutrition à Ch 14.1: The Physiology of Pregnancy p. 632-635; Changes in mother – weight gain in pregnancy Changes in the Mother •

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The continuous physiological adjustments a woman’s body undergoes during pregnancy affect the metabolism and distribution of nutrients in her body. - Maternal blood volume increases by 50% - Heart, lungs, and kidneys work harder to deliver nutrients and oxygen and remove wastes The placenta develops and the hormones it produces causes other changes: - Promotes uterine growth - Relaxes muscles and ligaments to accommodate the growing fetus and allow for childbirth - Promotes breast development - Increases fat deposition to provide the energy stores that will be needed during late pregnancy and lactation These changes result in weight gain and affects the type and level of physical activity that are safe for the pregnant woman

Weight Gain During Pregnancy • •

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Gaining the right amount of weight during pregnancy is vital to the health of both the mother and the fetus. The recommended weight gain for a healthy, normal-weight woman is 11.5 – 16 kg (25 – 35 lbs) - The weight of the infant at birth is typically around 25% of the total pregnancy weight gain. The placenta, amniotic fluid, and changes in the maternal tissues account for the rest. (Includes increase in the size of the uterus, breasts, expansion of blood and extracellular fluid volume, and deposition of fat stores The rate of weight gain is also important - In the first 3 months (trimester): little gain is expected à About 0.9 – 1.8 kg (2-4 lbs) - In the second and third trimesters (when the fetus grows from less than 0.5 kg to 3-4 kg), the recommended maternal weight gain is about 0.5 kg (1 lb)/week Underweight, overweight, and obese women at conception should still gain weight at a slow, steady rate. Weight gains of up to 18 kg (40 lbs) are recommended for women who begin pregnancy underweight Overweight women should gain 7–11.5 kg (15-25 lbs) during pregnancy

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Being underweight by 10% or more at the beginning of pregnancy or gaining too little weight during pregnancy increases the risk of producing a low-birth-weight baby or preterm baby. It can also increase the child’s risk of developing heart disease or diabetes later in life Excess weight before conception or gained during pregnancy can compromise the outcome of the pregnancy. The mother’s risks for high blood pressure, diabetes, difficult delivery, and Caesarean section are increased by excess weight, as is the risk of having a large-for-gestational-age baby. Maternal obesity may also increase the risk of neural tube defects and fetal death. - Despite this, dieting during pregnancy is not advised even for obese women - If possible, excess weight should be lost before the pregnancy. Ideally, women should have a BMI less than 25 or, if not possible, less than 30 when entering a pregnancy. - Large-for-gestational-age baby: an infant weighing more than 4 kg (8.8 lbs) at birth During pregnancy, women are encouraged to exercise to stay within recommended weight gains About 5 kg (10 lbs) are lost at birth from the weight of the baby, amniotic fluid, and placenta. In the week after the delivery, another 2.5 kg (5 lbs) of fluid are lost - Once this initial fluid and tissue weight is lost, further weight loss requires that energy intake be less than energy output. After the recovery from deliver, a balanced diet, with a small deficit of kcalories, combined with moderate exercise, will promote gradual weight loss and the return of muscle tone. - Gradual weight loss is important when the mother is breastfeeding, to ensure that milk production is not compromised 2006 Public Health Agency of Canada survey revealed certain patterns - A woman’s pre-pregnancy weight was found to be a good predictor of her weight gain during pregnancy. Women with BMIs greater than 27 gained the most weight during pregnancy. In contrast, less weight gain was observed in women with normal or low body weights. - Higher-than-recommended weight gain was more common among women having their first baby, among less educated women, and among Indigenous women - Women who gained more weight during pregnancy were also more likely to retain that extra weight after birth. This extra weight may contribute both to complications during pregnancy and to the development of obesity.

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The results of the previous survey discussed above indicates that the prenatal and postpartum care of Canadian women should be improved by providing more assistance in. weight management both during pregnancy and after the baby is born

Physical Activity During Pregnancy •

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Researchers also developed the Physical Activity Readiness Medical Examination form, which is available to physicians to access whether a woman can exercise during pregnancy or whether her particular pregnancy has contraindications such as medical conditions that recommend against exercise Healthy women without contraindications can safely engage in aerobic and strengthconditioning exercises with appropriate precautions - During pregnancy exercise should be focused on maintaining and modestly improving fitness levels not intense athletic training Benefits of exercise: - Improved maternal fitness - Less weight gain during pregnancy - Easier labour and deliver - Better posture and reduced back pain - Reduced risk of developing diabetes during pregnancy (gestational diabetes) - Reduced blood pressure The second trimester is considered the best time to begin an exercise program because the first trimester often comes with symptoms of fatigue and morning sickness. In the third trimester, the size of the developing fetus can limit some activities Guideline recommendations: - Aerobic exercise should be done for 150 minutes a week, over at least 3 days. Mothers who were previously sedentary should begin slowly, gradually increasing time, intensity, and frequency - Recommended activities are those that minimize the loss of balance and any possible trauma to the fetus such as brisk walking, stationary cycling, cross-country skiing, and aqua-fitness programs - Running and jogging are not advised because of potential damage to joints, which become more flexible during pregnancy Muscle conditioning should involve all major muscle groups with focus on promoting good posture and strengthening abdominal muscles and muscles of the pelvic floor that support the weight of the uterus.

à Ch 14.2: The Nutritional Needs of Pregnancy p. 639- 640, 641-647 Energy Needs During Pregnancy

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Energy needs increase during pregnancy to deposit and maintain the new fetal and maternal tissues The estimated energy requirement (EER) for pregnancy is calculated by totaling the energy needs of nonpregnant women, the increase in energy needs due to pregnancy, and the energy deposited in tissues During the first trimester, total energy expenditure changes little, so the EER is not increased above nonpregnant levels During the second trimester an additional 350 kcal/day is recommended while 450 extra kcalories/day is needed in the third trimester

Protein, Carbohydrate, and Fat Recommendations •

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RDA for protein during pregnancy is increased - Additional protein is required for the formation and growth of new cells. - During pregnancy the placenta develops and grows, the uterus and breasts enlarge, and a single cell develops into a fully formed infant - For the second and third trimesters an additional 25. G of protein per day above the RDA (or 1.1 g/kg/day) is recommended - Studies suggest that vegetarian women may have lower protein intakes than nonvegetarians, but there is no evidence that this lower intake is harmful to the fetus. RDA for carbohydrates during pregnancy is increased - An additional 45 g is recommended to provide adequate glucose to fuel the fetal and maternal brains Total fat intake does not need to increase during pregnancy - However, more of the essential fatty acids linoleic and alpha-linoleic acid are recommended because these are a component of the placenta and the fetal tissues - DHA, a fatty acid from fish oil or made in the body from the essential fatty acid alpha-linoleic acid is important in pregnancy because it functions in the development of the retina and brain in the fetus and infant. The best dietary source of DHA is fish. Infants born to vegetarian mothers who do not eat fish tend to have lower DHA levels in their blood. DHA levels in breast milk are also lower in vegetarians. Although the implications of these lower DHA levels are unclear, vegetarians and vegans should include sources of DHA in their diet from fortified foods or DHA supplements derived from microalgae, a non-animal product - A 2018 systematic review of randomized controlled trials found that increased longchain omega-3 fatty acid intake (EPA and DHA) reduced the risk of preterm birth and low-birth-weight babies. The recommended distribution of the macronutrients should be about the same as that recommended for the general population and should come from nutrient-dense choices.

Water and Electrolyte Needs

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The need for water is increased during pregnancy because of the increase in blood volume, the production of amniotic fluid, and the needs of the fetus. - From 2.7 L/day for nonpregnant women to 3 L/day in pregnancy During pregnancy, a woman will accumulate about 6 – 9 L of water - Some is intracellular, but most is due to increases in the volume of blood and interstitial fluid Despite changes in the amount and distribution of body water during pregnancy, there is no evidence that the requirements for potassium, sodium, or chloride are different from those of nonpregnant women

Micronutrient Needs During Pregnancy • • •

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The need for many vitamins and minerals is increased during pregnancy. Due to growth in maternal and fetal tissues as well as increased energy utilization, the requirements for the B vitamins (thiamin, niacin, riboflavin) increase. To form new maternal and fetal cells and to meet the needs for protein synthesis in fetal and maternal tissues, the requirements for folate, vitamin B12, vitamin B6, zinc, and iron increase. The needs for calcium, vitamin D, and vitamin C increase to provide for the growth and development of bone and connective tissue

Calcium •

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The fetus retains about 30 g of calcium over the course of gestation. With most of the calcium being deposited in the last trimester when the fetal skeleton is growing most rapidly, and the teeth are forming. Calcium intake does not need to be increased during pregnancy because calcium absorption increases during this time. - This increase may be due in part to the rise of estrogen during the pregnancy as well as an increase in the concentration of active vitamin D in the blood Increased need for calcium does not increase maternal bone resorption therefore the RDA for pregnant women remains at 1000 mg/day Women who are lactose intolerant can meet their calcium needs with yogurt, cheese, reduced-lactose milk, calcium-rich vegetables, fish consumed with bones, calciumfortified foods such as soy milk or calcium supplements

Vitamin D • •

Sufficient vitamin D is essential to ensure calcium absorption, but the recommended intake for vitamin D during pregnancy is not increased above nonpregnant levels Pregnant women who receive regular exposure to sunlight can make enough vitamin D

Vitamin C •

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Vitamin C is important for bone and connective tissue formation because it is needed for the synthesis of collagen which gives structure to skin, tendons, and the protein matrix of bones Vitamin C deficiency during pregnancy increases the risk for premature birth and preeclampsia RDA is increased by 10 mg/day during pregnancy (can be met in the diet and supplements are generally not necessary)

Folate • • • •

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Folate is essential in the synthesis of DNA and thus cell division. During pregnancy, cells multiply to form the placenta, expand maternal blood, and allow for fetal growth. Adequate folate is needed even before conception because rapid cell division occurs in the first days and weeks of pregnancy A low intake of folate poses a risk of fetal abnormalities that involve the formation of the neural tube which develops into the spinal cord and the brain. - During development, neural tissue forms a groove, this groove close when the sides rise and fold together to form the neural tube. This neural tube closure occurs between 21 and 28 days of development. If this does not form normally, defects include anencephaly (the brain and skull do not develop normally; this condition is fatal at or shortly after birth) and spina bifida (a condition in which the vertebrae do not close completely causing a part of the spinal cord to be exposed; this generally not fatal but can result in severe paralysis) Folate’s protective effect is likely due to involve the vitamin’s role in single-carbon metabolism and DNA methylation Recommendations are that women who could become pregnant consume a multivitamin with at least 400 mcg/day of synthetic folic acid in addition to consuming it in a varied diet For women with greater risk for neural tube defects supplements containing 1 to 5 mg of folate is recommended by the Society of Obstetricians and Gynecologists of Canada - Risk factors include: a) family history of NTD from either the maternal or paternal side b) impaired folate metabolism or absorption due to a medication or medical condition c) the presence of diabetes d) previous neural tube pregnancy Folic acid fortification decreased the incidence of neural tube defects by 50% in Canada Adequate folate continues to be important even after the neural tube closes. Cell division continues in both embryonic and fetal development and folate plays an essential role in DNA synthesis

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Marginal folate status can impair growth in both the fetus and the placenta. - If folate is inadequate, megaloblastic anemia (anemia in which blood cells do not mature properly) may result - Low dietary folate intakes and low circulating folate levels are associated with increased risk of preterm delivery, low birth weight, and fetal growth retardation RDA is set at 600 mcg/day of dietary folate equivalents and 400 mcg/day from folic acid supplements - Sources: orange juice, legumes, leafy green vegetables, organ meats, fortified sources

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Vitamin B12 is essential for the regeneration of active forms of folate, so a deficiency of this can also result in megaloblastic anemia Vitamin B12 is transferred from the mother to the fetus during pregnancy - Based on the amount transferred and the increased efficiency of vitamin B12 absorption that occurs during pregnancy, the RDA is set at 2.6 mcg/day - Vegetarian women are recommended to consume foods fortified with vitamin B12 or take supplements Low levels of vitamin B12 is also a risk factor for neural tube defects

Zinc • • • •

Zinc is involved in the synthesis of DNA, RNA, and proteins so it is crucial for growth and development. Deficiency of this mineral during pregnancy is associated with an increased risk of fetal malformations, prematurity, and low birth weight Iron supplements may compromise zinc status because zinc absorption is inhibited by high iron intakes RDA is 11 mg/day for pregnant women

Iron • • • •

Iron needs are high during pregnancy to allow for the synthesis of hemoglobin and other iron-containing proteins in both maternal and fetal tissues. The physiological changes of pregnancy allow for increased iron absorption and iron losses are decreased due to the cessation of menstruation However, iron deficiency anemia is still common in pregnancy - This may be due to low iron stores among women of childbearing age RDA for iron is 27 mg/day compared with 18 mg for nonpregnant women - Sources: red meats, leafy green vegetables, and fortified cereals - Foods that enhance iron absorption: citrus fruit and meat

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Iron supplements are recommended during the second and third trimesters of pregnancy Randomized controlled trials have shown that iron supplementation during pregnancy significantly reduces the risk of low-birth-weight babies Cohort studies have indicated that maternal anemia in the first and second trimesters of pregnancy is associated with an increased risk of low-birth-weight babies and preterm birth Preterm infants have lower iron stores at birth than full term babies

Meeting Nutrient Needs with Food and Supplements •

Energy and nutrient needs of pregnancy can be met by following the recommendation of Canada’s Food Guide

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Supplements of folic acid are recommended before and during pregnancy Iron supplements are recommended during the second and third trimesters A multivitamin and mineral supplement may also be needed if food choices are limited (vegetarian mothers) or if the mother’s needs are very high (pregnant teenagers) A prenatal supplement must be taken with (and not in place of) a carefully planned diet

Food Cravings and Aversions • • • •

Foods that are commonly craved include fruit and fruit juices, sweets, candy, chocolate, and dairy products Common aversions include coffee and other caffeinated drinks, alcohol, meat, fish, poultry, eggs, highly seasoned foods, or fried foods Hormonals or physiological changes during pregnancy (changes in taste and smell) may be the cause of cravings and aversions Abnormal cravings leading to the consumption of non-food substances (a condition called pica) poses serious consequences - Potential causes: a) A way to meet cultural expectations b) Reduce psychological stress c) Alleviate hunger d) Reduce indigestion e) Provide micronutrients such as calcium, iron, and zinc f) Protect against toxins and pathogens - Commonly consumed materials: soils and clays (contains iron, zinc, and calcium and also has the capacity to bind toxins and bacteria)

à Ch 14.3: Factors that Increase the Risk of Pregnancy p. 648-655 Maternal Nutritional Status Nutritional Status Before Pregnancy •

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Starvation diets, anorexia nervosa, and excessive exercise such as marathon running can reduce body fat and affect hormone levels. If hormone levels are too low, ovulation does not occur, and conception is not possible Too much body fat can also reduce fertility by affecting hormone levels Deficiencies or excess of nutrients can also affect pregnancy outcome - Deficiency of folate or an excess of vitamin A early in pregnancy can cause birth defects Nutritional status can be affected by some birth control methods - Oral contraceptives are associated with reduced blood levels of folate, vitamin B6, and vitamin B12. If conception occurs soon after the cessation of oral contraceptives, these levels would not have had adequate time to return to normal.

Malnutrition During Pregnancy • •

Causes fetal growth retardation, low infant birth weight, birth defects, premature birth, spontaneous abortion, and stillbirth In general, poor nutrition early in pregnancy affects embryonic development and the potential of the embryo to survive, and poor nutrition later on in pregnancy affects fetal growth

à Immediate effects • •

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A low energy intake during pregnancy is not likely to interfere with fetal growth because energy demands of the embryo are small However, if the embryo does not receive adequate a...