Module 1: Nutrition and Weight Gain During Pregnancy. Text

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1 Slide 1 Slide 2 Slide 3 Welcome to the module Nutrition and Weight Gain During Pregnancy This is the first module in the Maternal and Infant Nutrition series. In this module we will discuss the factors behind altered nutritional needs in pregnancy as well as specific nutrients of concern for many women during pregnancy. We will start with the topic of physiological changes that occur during pregnancy. During pregnancy there are many physiological changes that occur, with many of them beginning soon after conception. This has implications for nutrient needs and dietary intake. In general, nutrient needs will be highest when fetal growth is the highest. These physiological changes include increased need for macro- and micronutrients involved in protein, RNA and DNA synthesis, increased need for oxygen transport, altered metabolism of macronutrients, increased absorption of micronutrients, decreased motility of GI tract, and increased renal load. We will be discussing individual nutrient needs in future slides. Slide 4 The cardio-respiratory system experiences dramatic changes during pregnancy. Resting oxygen consumption increases 20-30%, coinciding with fetal growth as well as an increased metabolic rate and need for calories in the mother. Blood volume increases by about 40%, gradually increasing throughout the pregnancy until it peaks around the middle of the third trimester. Plasma volume increases by 50%. Cardiac output is stabilized earlier in pregnancy, usually around the early part of the 3rd trimester. Because cardiac output stabilizes before blood volume expansion is complete, many women develop fatigue and have lower tolerance for physical activity. It is important to remember that increases in blood and plasma volume will be greater in women with multiple pregnancies than in singleton pregnancies, so these women may experience fatigue earlier in pregnancy and may not tolerate physical activity well in the later half of pregnancy.

2 Slide 5 An increase in red blood cell mass occurs throughout pregnancy to supply oxygen and other components to mom and the rapidly growing fetus. However the increase in Red Blood Cell mass is considerably smaller than the increase in plasma volume, resulting in hemodilution. This phenomenon causes an overall decrease in hematocrit and hemoglobin during pregnancy. Also, it is important that appropriate laboratory reference values are used during pregnancy as pre-pregnancy reference values will not be valid. Slide 6 Renal function changes during pregnancy because the kidneys work overtime so that mom can process the byproducts of fetal waste as well as her own. Blood flow to the kidneys is increased as is the glomerular filtration rate. Overall, there is an increased excretion of protein, calcium, phosphorous and some water soluble vitamins. There is also in increase in the reabsorption of electrolytes, glucose and water which provide fuel for the fetus. Excessive stress on the renal system may lead to a higher risk for hypertension during pregnancy for some women. Some women will revert to normal afterwards and some will not. Slide 7 Throughout pregnancy there are changes in metabolism which support maternal and fetal health. Most of these metabolic adaptations are designed to promote fetal development through increased production of glucose and fatty acids. Metabolic adaptations include: increased maternal use of gluconeogenic amino acids, increased maternal fat oxidation, increased production of ketones, and increased hepatic glucose production. How do you think we could close the participant folder using the menu options? Go ahead.

3 Slide 8 Carbohydrate metabolism is altered during pregnancy. Blood glucose levels are generally 10-20% lower in pregnancy, which can cause even well-controlled diabetic women problems early in pregnancy. Overnight fasting blood glucose levels are mg/dl lower in most women during pregnancy, increasing the need for dietary counseling. Carbohydrate metabolism shifts in midpregnancy. In the first 20 weeks, there is an increased insulin production and conversion of glucose to glycogen and fat. During the last half, there is an increased level of insulin resistance. This is the reason that women are screened for gestational diabetes in midpregnancy and not earlier. In addition, the last 20 weeks there is less conversion of glucose to glycogen and fat, increased hepatic glucose production, and increased flow of glucose, VLDL and amino acids to the fetus. Slide 9 Triglyceride levels begin to increase early in pregnancy and continue to rise throughout pregnancy. Body fat is accumulated in early pregnancy. Mobilization of this body fat occurs in the second half of pregnancy as fetal needs are increased. Most women will experience significant changes in body fatness in their upper body in later pregnancy. A lot of the fat is deposited in the arms and some in the thighs. Interestingly, adolescent females who are within 2-4 years of menses do not seem to mobilize body fat in the third trimester in the same way adult women do. This is likely because they are still in an active growing process themselves and their own hormones override this loss of body fat. This has raised concerns about the use of adult weight gain recommendations in adolescents. At this point there is not adequate data to change those recommendations but studies are currently underway to examine this issue.

4 Slide 10 There is also a change in lipid metabolism. Triglycerides are increased throughout pregnancy and free fatty acids are increased after 30 weeks gestation. Adipocytes hypertrophy in the first half of pregnancy to promote fat storage and reductions in size are noted in the last half of pregnancy as lipolysis increases. Insulin is involved with the early pregnancy deposition of maternal body fat, probably through an increased number or sensitivity of insulin receptors on adipocytes. When insulin resistance occurs later in pregnancy, fat is mobilized. The increase in insulin receptors on adipocytes facilitates fat storage. Slide 11 Although there are alterations in protein metabolism during pregnancy, they are not significant. There is an increase in protein storage in early pregnancy, and later in pregnancy this is released. Serum amino acids and protein levels are decreased due to increased insulin levels, placental uptake, and gluconeogenesis. Also, there is a decrease in urea production and secretion. Lastly, the kidneys conserve amino acids during rapid fetal growth. Slide 12 There are many hormones required to support a healthy pregnancy and they are listed with their origin of secretion. We will discuss these in terms of how they affect nutritional needs in pregnancy in the next few minutes. Slide 13 Other hormones are also involved with metabolic shifts during pregnancy. It is important to remember that there are 2 distinct metabolic periods during pregnancy. In the first half of pregnancy, metabolism is anabolic for Mom. Pregnant women will increase stores of glycogen and fat in anticipation of increased fetal growth. During the second half of pregnancy metabolism shifts dramatically toward a maternal catabolic state. Mom becomes mildly insulin resistant, resulting in a net increase in glucose flow to the fetus. As fetal growth increases, Mom will metabolize stored body fat in order to supply adequate fatty acids to the fetus. This shift in glucose and fat metabolism occurs around weeks of gestation, coinciding with the timing of greatest risk for the development of gestational diabetes.

5 Slide 14 Now that we have covered the physiology and metabolism of pregnancy, we ll talk more about weight gain in pregnancy. Slide 15 Slide 16 Slide 17 These are the Institute of Medicine guidelines for weight gain in pregnancy. They were adopted in There are several differences between the 2009 guidelines and the previous guidelines from The changes include: BMI categories are now in line with the CDC threshold for obesity, weight gain range for obese women was altered, and the old guidelines did not address twin pregnancies. The 2009 guidelines have set 3 recommendations for women during twin pregnancy, based on weight status. The expert panel failed to find enough evidence to set a weight gain recommendation for underweight women with twin gestation. They also did not find adequate evidence to set a weight gain recommendation for higher order pregnancies. Research data suggests that triplet and higher pregnancies require at least 55 lb of weight gain or more. This is a breakdown of where weight goes during pregnancy. These data were used to determine the 1990 IOM guidelines. As you will note, the amount of weight gained in obese or very obese women does not have a large effect on infant birthweight, increasing it by only about grams on average. The lower a woman s weight prior to pregnancy, the more beneficial increasing weight gain is on infant birthweight. Slide 18 These are data used to determine the 2009 IOM guidelines. Note the similarities in data from the previous slide. As discussed earlier, gestational weight gain has a significantly greater impact on birth weight among underweight and ideal weight women than it does on those with a BMI greater than 25. The impact of weight gain in obese women on infant birth weight is small.

6 Slide 19 One major concern in maternity care at this point is that most women do not gain within the IOM recommended ranges. Less than 1/3 of women achieve the recommended gain. About ¼ of women gain too little and almost half of women gain too much weight during pregnancy. When the IOM expert panel met, they identified that future research needs to focus on ways of promoting optimal weight gain among women, rather than changing the existing guidelines. Data from the CDC Pregnancy Nutrition Surveillance System illustrates changes in weight gain among women of different racial/ethnic groups across a 10 year span. The number of women gaining below the IOM guidelines has decreased among all women except those of American Indian descent. The number of women gaining above the IOM guidelines has increased among all women. Slide 20 Women who gain below the IOM guidelines are at greater risk of LBW, preterm birth and Full term LBW compared to women who gain within or above the guidelines. These data from the CDC show that gaining weight within the IOM recommendations decreases risk of poor infant outcomes including low birthweight, preterm birth and full term low birthweight (AKA intrauterine growth restriction)

7 Slide 21 The rate of weight gain in pregnancy is possibly more important than the overall gain. Weight gain in the first trimester is largely related to maternal tissue changes and blood volume and not highly related to fetal growth. Rates of recommended gain increase throughout pregnancy as fetal growth increases. Rate of gain is an important clinical tool. If a woman has had a steady rate of gain throughout pregnancy but suddenly weight gain stops or decreases, this may indicate some level of fetal distress, changes in placental nutrient transfer or other risk factors for preterm delivery or poor infant outcomes. A woman who had marked nausea and vomiting early in pregnancy, resulting in moderate weight loss, but has adequate gain throughout her second and third trimesters will likely deliver a healthy birth weight infant even if her total weight gain is somewhat low due to early weight loss. Conversely, a woman who gains excessively early in pregnancy but has a low rate of gain in the third trimester may deliver a low birth weight infant despite appearing to have an adequate overall weight gain. Slide 22 Data from several studies suggest that low weight gain in the third trimester is an important predictor of preterm delivery. Low weight gain in the second trimester of pregnancy also predicts low birth weight risk, but not quite to the same extent. This make sense since fetal growth increases throughout most of pregnancy. Carol Hickey s data from Alabama suggests that low weight gain is more predictive of preterm birth among white women than among black women. This may be a racial/ethnic difference or it may be the result of black women having a greater number of other risk factors that contribute to preterm birth, such as poverty, lower education and other stressors. For the reasons mentioned earlier and based on this data from Barbara Abrams at UC Berkley, rate of gain is always a better predictor of pregnancy outcomes than is total weight gain.

8 Slide 23 As mentioned earlier, the recommended weight gain for normal weight women is lbs. Women who gain lbs have a higher risk of complications, such as: hypertension, pre-eclampsia, and high infant birth weight of over 9 lbs. Women who gain over 44 lbs have a higher risk of requiring an assisted delivery, such as a Cesarean section. Slide 24 Obese women who gain more than the recommended lbs have increased risk of complications. These complications include: hypertension, induction of labor, shoulder dystocia, infant birth weight over 9 lbs, and large for gestational age infant. Trends in increased risk for all maternal and fetal complications are noted with increasing weight gain. Slide 25 Slide 26 A recent area of controversy is whether or not the IOM BMI cutpoints are appropriate for use among pregnant adolescents. The cutpoints used in the IOM are based on adult data and do not coincide with CDC cut-points for teenagers. Data have shown that young adolescents, especially those less than 16 years of age, are very likely to misclassified when the IOM BMI cutpoints are used. As many as 50%-75% of young adolescents would be told to gain too much weight as they would be classified as underweight prior to pregnancy rather than normal weight (based on 1990 cutpoints newer guidelines would result in fewer teens being misclassified). This is an area that needs further investigation and may result in revision of clinical practice. Now we will discuss specific nutrient needs in pregnancy.

9 Slide 27 In general, there are 3 main goals for nutrition assessment and treatment during pregnancy. The first and most often cited goal is to optimize the birthweight of the infant through adequate maternal weight gain, prevention of preterm delivery, prevention of intrauterine growth restriction and prevention of macrosomia ( which is also known as large for gestational age ). Birth weight is also optimized through appropriate weight gain and rate of weight gain and optimal nutrient intake. The second goal is to prevent congenital anomalies through optimal nutritional status. The third is to prevent or manage pregnancy complications that have nutrition underpinnings, such as anemia, hypertension and gestational diabetes. All of these goals are important aspects of prenatal care. Slide 28 Getting adequate protein, energy and essential fatty acids in pregnancy is important. Adequate energy intake is necessary to support recommended weight gain at recommended rates, adequate protein is important to supply amino acids to the fetus, and adequate intake of essential fatty acids is necessary to make myelin and cell membranes. Adequate intake of vitamins and minerals is important to support fetal growth without compromising mother s status. Some nutrient needs are increased in pregnancy while others are not. We will discuss in greater detail those nutrients whose needs are increased the most as well as those that most women are deficient in. Slide 29 An overall healthy balance of macronutrients is required in pregnancy just as it is in the non-pregnant state. Additional calories should be taken in through nutrient dense foods that supply nutrients needed in pregnancy. The old advice of eating for two should not be used as it encourages over consumption and excessive weight gain.

10 Slide 30 Energy needs of women in the first trimester are not high. A glass of orange juice or a slice of toast will meet additional needs in the first trimester. The second trimester needs are higher by about 300 Kcals. A bowl of cereal with lowfat milk or half a sandwich on whole wheat bread would meet additional energy needs. The third trimester needs peak at about weeks gestation. A significant snack, or two small snacks will meet the needs of most women. Carbohydrate and protein needs are increase throughout pregnancy but most women who are not food insecure or who do not have significant nausea/vomiting are able to meet these needs. Slide 31 The new DRIs are the first guidelines to specify intakes of essential fatty acids in pregnancy. These were set at levels that appear to provide optimal, but minimal, intake to promote adequate infant development while meeting Mom s needs. It is important to note that while there are specific increases in needs for protein and carbohydrate, fat intake is a range that varies according to the energy needs of the mother. Fluid needs were determined to be 3 liters per day according to the new DRI values. This level is set to provide adequate hydration for mom, provide optimal fluid intake to promote amniotic fluid balance and to provide fluids at a level that minimizes the risk of urinary tract infections. Slide 32 Women at greatest risk for deficient intakes of essential fatty acids are those who consume vegan diets and do not supplement intake with additional sources of essential fatty acids. Other women who may be at risk are those who frequently consume highly refined, processed foods that are high in trans fats. These women may need to take essential fatty acid supplements or take a prenatal vitamin that contains these nutrients.

11 Slide 33 DHA has received a great deal of attention in the last few years. DHA can be made from α-linolenic acids within the body, however the conversion in adults is not high. Decreased intakes of DHA have been shown to reduce fetal stores of DHA and may affect early visual recognition in infants. There are no data to date that have shown that higher intakes of DHA results in lifelong increases in intelligence, visual acuity or any other health benefits. The research that does show benefits in children suggests that the benefits are no longer very apparent by 2-3 years of age. This makes sense since, by that age, children will have been consuming the majority of their energy from solid foods and their intake of DHA will be a better predictor of DHA status than that of their mother during pregnancy Slide 34 The foods listed on this slide are the primary sources of α-linolenic acid in humans. Vegan women should include 1-2 Tablespoons of walnut, soybean or flaxseed oil per day in their diet during pregnancy to provide essential fatty acids. Additional amounts of these fats can be used if energy needs allow. Slide 35 This slide illustrates sources of DHA in humans. Fish is the primary source of DHA for adults. Women who are allergic to finfish or shellfish may benefit from a DHA or fish oil supplement. Slide 36 Much controversy surrounds the inclusion of fish and seafood in the diets of pregnant women and children. Data from the EPA and independent researchers suggest that there are some fish that should be avoided during pregnancy and other fish that are safe in moderate amounts. Any fish that is a large fish, feeding on smaller fish, has the potential to concentrate higher amounts of mercury and other contaminants. Therefore, these fish (albacore tuna, swordfish, walleye, bass, etc) should be avoided. Fish that appear to be safely consumed at levels of 4-12 ounces per week in pregnancy included chunk light tuna, salmon, cod, sole and shellfish.

12 Slide 37 Listed on this slide are the DRI values for women prior to pregnancy and during pregnancy, as well as the upper limit of intake for select nutrients. When adolescents have a DRI that is different from adults, it is noted in parentheses. In general, needs for most B-vitamins and minerals are increased during pregnancy. Adolescents have higher needs for calcium, phosphorous and magnesium due to continued bone development. They have slightly lower requirements for Vitamins A and C. Slide 38 Slide 39 Folate is also referred to as folic acid. Low folate status is associated with congenital anomalies, such as neural tube defects. Low intake is also associated with poor maternal and infant outcomes including increased risk for low birthweight, pre-eclampsia and preterm delivery. Folate has to be present during the first days of pregnancy for development of neural tube. Many women do not consume adequate folate during pregnancy. Due to the early need of folate, supplementation prior to and during pregnancy is recommended. The graph illustrates how folic acid awareness and use among US women changed between 1995 to 2007 Slide 40 Neural tube defects are common birth defects that have been shown to be at least partially preventable through optimal folate intake prior to and during the first few weeks of pregnancy. Folic acid intake is most effective in preventing neural tube defects when consumed in adequate amounts prior to pregnancy because it takes approximately 2 weeks for red blood cell folate levels to rise based on dietary intake. Neural tube defects occur in the first 2-4 weeks of pregnancy and most women will not know they are pregnant for at least 2-3 weeks into the pregnancy. In addition, about half of all preganancies are unplanned. This means that folate supplements begun when women know they are pregnant are not likely to be able to prevent against neural tube defects. The purpose of folate fortification in foods is to provide folate in commonly consumed foods, such as bread and cereal, to work to prevent neural tube defects. With the mandatory fortification, the rate of neural tube defects dropped 19% within 2 years.

13 Slide 41 Folate/Folic acid supplement use has decreased among women of reproductive age, despite national campaigns to promote folate. There is a need for health professionals to promote folate supplementation among all females starting at or before menses. Changes in Folate Status : For the past decade, it was assumed that folate status was improving among women because of supplementation. However national data from NHANES suggests that folate status has actually decreased among women over the past decade. Low carbohydrate diets have been shown to be a factor associated with decreasing intakes of folate, as grains are main sources of folate in the diets of American women. Another factor is obesity. Several strong studies have shown that overweight/obese women have lower folate status than normal weight women even when dietary intakes are the same. Research is on-going as to why this occurs, and it seems that alterations in folate metabolism are a likely factor. Obese women are 24% less likely to take a folate supplement even after adjusting for race/ethnicity, age, education, and income. Slide 42 Low iron levels increase the risk for prematurity, low birth weight, and poor maternal weight gain.the recommended dietary allowance is 27 mg per day. Less than 30% of women get enough iron in the diet. The absorption of iron is increased in pregnancy. The absorption varies depending on intake and other dietary compounds. Since, iron intake in pregnancy is generally well below recommended levels, iron supplementation is recommended for all women after the 12th week of pregnancy when needs increase. High levels may be prescribed in the presence of iron deficiency, however, compliance with iron supplementation is notoriously low due to the many side effects.

14 Slide 43 Poor zinc status in pregnancy has been linked to a variety of poor pregnancy outcomes including preterm delivery, low birth weight, prolonged labor, intrauterine growth restriction, hypertension, maternal hemorrhage, congenital anomalies. Vegan women and those who do not consume adequate amounts of animal protein should be advised to take a supplement containing zinc during pregnancy. Less than 60% of women consume adequate amounts of zinc from diet. Slide 44 Calcium is needed in higher amounts in pregnancy to support fetal growth needs. Low intakes of calcium have been linked to hypertension and/or pre-eclampsia especially among young women. Smaller effects on birth weight have been found in some, but not all, studies. Less than 25% of women get adequate amount of calcium from diet alone. Supplements are often recommended to ensure adequate intake. Calcium citrate, calcium carbonate and calcium lactate are the best sources of supplemental calcium for women. It is important that pregnant women avoid using natural or organic sources of calcium. These sources, also called bone meal or oyster shell calcium, may be contaminated with lead, mercury and other heavy metals which are toxic in large amounts to the fetus. Slide 45 Vitamin A is a nutrient that can be toxic at high levels, especially early in gestation. Females using topic acne preparations that are retinol based should discontinue use. Excessive intake of retinol or use of isoretinoin increase the risk for central nervous system abnormalities, cardiac and craniofacial defects, and thymus malformation. Vitamin A deficiency is not commonly seen in the US except among some women who have recently immigrated to the US from refugee camps. For these women, supplementation prior to and during pregnancy based on measured vitamin A status is recommended.

15 Slide 46 Slide 47 Adolescents have some needs that are specific to them during pregnancy. Nutrient needs, especially for minerals, may be higher for pregnant teens than for adult women as their baseline needs may be elevated due to growth. Energy needs should be based on their recommended energy intake with the same amount of additional calories added as for adult women. Weight gain in pregnant teens may reflect both fetal growth and the mother s growth so it becomes very difficult to determine if the recommended rates of weight gain and total weight gain guidelines for adults are appropriate for teens. Now it is time to test your knowledge! Slide 48 Slide 49 Question 1: Changes seen in pregnancy do not include: A. Increase in oxygen consumption B. Increase in blood volume C. Increase in GI tract motility D. Increase renal excretion of certain nutrients. Answer: C. The GI tract motility decreases during pregnancy. Question 2: What is the recommended weight gain during pregnancy for women with normal prepregnancy weight status? A lbs. B lbs. C lbs. D lbs Answer: B. The recommended weight gain during pregnancy for women with normal prepregnancy weight status is lb. Slide 50 Slide 51 Question 3: What are the complications associated with high maternal weight gain? A. Hypertension B. Pre-eclampsia C. high infant birth weight D. Assisted delivery E. all of the above Answer: E. All of the above Question 4: The main nutrition concerns in pregnancy include adequate energy, protein, essential fatty acids, and vitamin and mineral intake. A. True B. False Answer: A. True

16 Slide 52 Slide 53 Slide 54 Question 5: Which of the following is most commonly consumed in adequate amounts in the US? A. Vitamin A B. Iron C. Calcium D. Folate E. Zinc Anwer: A. Vitamin A is typically consumed in adequate amounts compared to iron, calcium, folate and zinc. Quiz Result This completes the module Nutrition and Weight Gain During Pregnancy, presented by the Minnesota Department of Health WIC Program