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Obesity in What every Pregnancy nurse needs to know
What every
Sandra K. Cesario, RNC, PhD
nurse needs to know.
O
besity has become an epidemic in America, and most experts consider it an obstetric hazard. It coexists with and is perceived to be the cause of many forms of obstetrical and neonatal morbidity or mortality and, as a result, has an enormous impact on the health of women and their children. Experts at the U.S. Department of Health and Human Services, Centers for Disease Control and Prevention (1999) report that 61 percent of U.S. adults and almost 20 percent of U.S. adolescents of childbearing age (12 to 19 years) are overweight or obese. Obesity affects all organ systems; excessive weight contributes to a multitude of physiological complications that include, but are not limited to (Edwards, Hellerstedt, Alton, Story, & Himes, 1996; Garbaciak,
Richter, Miller, & Barton, 1985; Gross, Solcol, & King, 1980; Jung, 1997; Kaiser & Kirby, 2001; Steinfeld et al., 2000; Wang, Davies, & Norman, 2000), • • • • • • • • • • •
hypertension vascular disease diabetes birth trauma infertility hemorrhage respiratory difficulty musculoskeletal strain cancer birth defects higher rates of cesarean section
Neonatal complications may also be related to maternal size (Manzar, 2000). Psychosocial problems associated with obesity include depression, poor self-esteem and social discrimination. Obesity increases the risk of lifelong medical conditions more than smoking or alcohol abuse (Warner, 2002). Obese women are at high risk for childbearing complications and require vigilant nursing assessment and care throughout pregnancy and birth. As the epidemic of obesity increases in America, nurses will care for greater numbers of obese women. Being prepared to aggressively manage the special needs of these women and their infants will promote positive birth outcomes for these childbearing families.
Pacific nations, feminine obesity is seen as a positive physical attribute and thought to increase the value of the woman as a mate and childbearer (Scieve, Cogswell, & Scanlon, 1998). In North America, more poor women are obese than are middleclass or wealthy women (Sauer, 1992). Endocrine disorders most commonly cited as playing a role in obesity during pregnancy are thyroid and pancreatic dysfunction. Pregnant patients are routinely screened for these disorders. Thyroid problems account for less than 1 percent of maternal obesity (Heard, 2000) while pancreatic dysfunction as gestational diabetes is estimated to occur in 6 percent of all pregnancies (Olds, London, & Ladewig, 2000).
Exploring Obesity
Defining & Tracking Obesity
Obesity is a multifactorial condition with genetic, neurologic, behavioral, sociologic and/or endocrinologic components (Heard, 2000). While adipose tissue is necessary for metabolic function, obesity is an excess of body fat that results in increases in both size and number of fat cells in the body. The genetic basis for obesity is a widely accepted and a well-documented contributor to this condition. Twin studies indicate that monozygotic twins are more likely to demonstrate similar weight gain patterns than dizygotic twins (Allison et al., 1996; Stunkard, Foch, & Hrubec, 1986; Stunkard, Harris, Pedersen, & McClearn, 1990). In addition, studies of adopted children indicate that a child is more likely to be of similar weight distribution of the genetic parents than of the adoptive parents (Stunkard et al., 1986a, 1986b; Vogler, Sorensen, Stunkard, Srinivasan, & Rao, 1995). While obesity and its associated risks cross all ethnic and social strata, the incidence for black women is twice as high as it is for white women (Kaiser & Kirby, 2001; Kuczmarski, Flegal, Campbell, & Johnson, 1994). Neurologically, certain lesions in the hypothalamus can provoke hyperphagia and lead to obesity. There is also evidence linking particular neurotransmitters such as serotonin and the catecholamines to satiety (Kalra et al., 1999). When there is an interruption in the neurotransmission of these chemicals, there is an increase in appetite that may result in a person gaining excessive weight. A wide variety of sociologic and behavioral factors have been implicated in obesity. Learned dietary habits during childhood, using food as a reward or as an aid to manage stress or depression, larger portions of high-fat foods being served in American restaurants, night eating, and sedentary lifestyle are just a few of the factors leading to an overweight society (Jung, 1997). Obesity in Western society is unlike many other societies throughout the world where obesity is associated with wealth and a high level of social status. In the Far East and
A wide variety of definitions are used in the literature to define obesity, making it difficult to compare studies on this topic. The three most common ways used to describe obesity in health-related journals include (Weiss & Malone, 2001),
Sandra K. Cesario, RNC, PhD, is assistant professor in the College of Nursing at Texas Woman’s University–Houston Center. DOI: 10.1177/1091592303253864
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• the percentage of ideal body weight • body mass index (BMI) • absolute body weight Being obese can also be determined by (Bowers & Cohen, 1999), • having a pre-pregnancy or pregnancy weight of more than 200 pounds (more than 90 kg) • being greater than 110 percent of ideal body weight at the first prenatal visit • having a BMI greater than 30 Also, many authors use additional descriptive terminology to delineate degrees of obesity. Terms used in association with “obese” include slightly, moderately, massively, morbidly, markedly or grotesquely. The specific definitions of each of these terms vary among studies. The incidence of obesity has been steadily increasing worldwide. The World Health Organization considers obesity a global epidemic and public health problem as more nations become “Westernized” (Warner, 2002). Worldwide, the prevalence of obesity has increased by more than 8 percent during a 15-year period (Mokdad et al., 1999). In the U.S., the average American gains an average of one pound per year after the age of 25. Because muscle and bone mass decrease with age, the percentage of body fat becomes exaggerated. As such, Americans typically add more than 37 pounds of fat to their bodies by the time they reach age 55 (Warner, 2002). Although obesity is more prevalent in lower socioeconomic groups in the U.S., its incidence appears to be increasing in young adults with a college education (Kuczmarski et al., 1994; Mokdad et al., 1999). African American women are more overweight than Caucasian women, but African American men
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Body Mass Index (BMI) is the most common single tool used in determining obesity (see Box 1, “Gauging BMI”). BMI is a weight-to-height ratio calculation that can be determined by dividing a woman’s weight in kilograms by her height in meters squared. BMI may also be calculated by weight in pounds divided by the height in inches squared, multiplied by 704.5. Pre-printed charts are widely available to determine BMI. Experts at the Centers for Disease Control and Prevention categorize BMI as follows: • • • •
Box 1.
underweight: less than 18.5 healthy weight: 18.5 to 24.9 overweight: 25 to 29.9 obese: 30 or higher
Hip-to-waist ratio or skin-fold determinations more accurately assess the percentage of body fat. Densitometry, ultrasound and CAT scans have also been used to assess distribution of adipose tissue (Heard, 2000).
Gauging BMI Use these handy resources for fingertip information regarding obesity and body mass index calculations: • BMI Calculator for Palm OS: http://hin.nhlbi.nih.gov/bmi_palm.htm • Obesity Guidelines for Palm OS: http://hin.nhlbi.nih.gov/obgdpalm.htm • Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults: http://www.nhlbi.nih.gov/guidelines/obesity/ ob_home.htm
weigh less than Caucasian men. Hispanic women and men are more likely to weigh more than their Caucasian counterparts (Steinfeld et al., 2000). In men, BMI tends to increase until it plateaus around age 50. In women, this plateau does not occur until age 70. The three high-risk periods for weight gain in women are • at the onset of menstruation • after pregnancy • after menopause
Assessing Risk Both pregnancy and obesity are associated with distinct physiologic alterations that accentuate each other, making assessing, diagnosing and providing care for an obese pregnant woman complex and challenging (Sauer, 1992). In most cases, visual inspection of the patient provides sufficient information to elicit further investigation of weight gain pattern. Obtaining a family and individual history of body weight patterns is helpful in predicting the patient’s growth curve. Carefully maintaining weight and height graphs is essential.
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Pathophysiologic Changes Related to Obesity Most antenatal problems are due to medical conditions that often coexist with obesity. Hypertension, diabetes, pyelonephritis and obstructive sleep apnea occur quite frequently and complicate the care of pregnant women. As many as 40 percent of obese women have chronic hypertension (Ruge & Andersen, 1985; Weiss & Malone, 2001), and another 27 to 38 percent of obese women will develop pregnancy-induced hypertension (Isaacs, Magann, Martin, Chauhan, & Morrison, 1994; Rossner, 1998). Both pregnancy and obesity increase cardiac workload and myocardial oxygen consumption. Cardiac output in an uncomplicated pregnancy increases by 35 to 40 percent; in an obese woman, it increases by 50 percent. A higher left ventricular preload may lead to increased edema. Obesity hypoventilation or “Picwickian Syndrome” (named in reference to the Dickens character, Fat Joe, in the “Pickwick Papers”) might be suspected if a woman complains of sleepiness during the day, snoring or waking frequently during the night (Sauer, 1992). This condition may lead to pulmonary hypertension and may be fatal if left untreated. An increase in body weight also places excessive strain on the musculoskeletal system. Lumbar lordosis, normally present in all pregnancies to provide balance as the uterus enlarges, is exaggerated by obesity. An obese pregnant woman also may develop a thoracic kyphosis. Excessive weight increases the work of the back and leg muscles and may result in backache, leg pain, increased fatigue and aggravated varices. Skeletal changes in addition to the weight of the chest wall, breasts and viscera increase respiratory workload and lower oxygen saturation. An obese woman also may have a reduced carbon dioxide response, leading to an increased risk of
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hypoxemia with the administration of drugs that depress respiration such as narcotics and sedatives (Sauer, 1992). The incidence of obstructive sleep apnea is pronounced in this population as body weight exerts pressure on the diaphragm and airway when such a person is in a supine position (Lefcourt & Rodis, 1996; Lewis et al., 1998). These women are also at increased risk of developing hiatal hernia and markedly elevated gastric emptying times. Antenatal urinary tract infections, often resulting in pyelonephritis, occur more frequently in obese pregnant women. Diabetes is more prevalent when pregnancy and obesity coexist. Up to 19 percent of obese pregnant women have pregestational diabetes, and another 8 percent develop gestational onset diabetes (National Institutes of Health, 1998). With diabetes, the pancreas doesn’t produce sufficient insulin for carbohydrate metabolism. Cells become energy depleted while the blood glucose level remains elevated. These changes contribute to a higher incidence of (Dye, Knox, Artal, Aubry, & Wojtowycz, 1997; Edwards et al., 1996), • • • • • •
hydramnios hypertension hyperglycemia fetal macrosomia intrauterine growth retardation congenital malformations
Central fat deposition provokes more disordered glucose tolerance than peripheral fat distribution (Hora & Fraser, 2000). Obesity and adult onset diabetes are risk factors for venous thromboembolism (VTE). Adults with a BMI of at least 40 are nearly three times more likely to develop VTE than adults with a BMI of less than 25. Adults with diabetes are nearly twice as likely as persons with normal fasting glucose levels to be diagnosed with VTE (Heit et al., 2002). Complications experienced during the intrapartum period are markedly increased when the laboring woman is obese. Women in this group experience up to 55 percent more of the following complications (Kaiser & Kirby, 2001): • • • •
cesarean delivery shoulder dystocia blood loss anesthesia difficulties
Higher cesarean delivery rates are associated with fetal macrosomia and soft tissue dystocia. In addition, cesarean delivery is often complicated by excessive operative blood loss (greater than 1,000 cc’s), difficult intubations and operative times greater than two hours (Perlow & Morgan, 1994; Weiss & Malone, 2001). Vaginal birth in this group is complicated by a 30 percent rate of fetal macrosomia contributing to dysfunctional labor patterns, prolonged labor, perineal and bladder trauma and shoulder dystocia. Epidural anesthesia is more difficult to initiate and
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maintain when a woman is overweight, often requiring repeated placements of the epidural catheter to achieve success (Hood & Dewan, 1993). Assessment of the fetus and labor progress via electronic monitoring or palpation may also be difficult due to the thick layer of adipose tissue covering the uterus. Complications of obesity extend also into the postpartum period. Excessive postpartum bleeding occurs more often and may be related to decreased muscle tone, inability to palpate the fundus, macrosomia and decreased physical activity (Edwards et al., 1996). Obese women also experience increased incidence of postoperative wound infection, dehiscence and delayed healing. Endometriosis, occurring at a rate of 45 percent, complicates the postpartum course in women weighing more than 300 pounds (Bowers & Cohen, 1999). Deep vein thrombosis and pulmonary embolism occur more frequently when a postpartum woman is overweight. Many other complications are more prevalent with obesity and should be kept in mind when individualizing care for a pregnant, obese woman. Overweight and obesity are associated with an increased risk for some types of cancer, including, • • • • •
endometrial colon gallbladder kidney postmenopausal breast cancer
The risk for developing arthritis increases by 9 to 13 percent for every two-pound increase in weight. Gall bladder disease, incontinence and depression are more common. Quality of life and an ability to parent may be affected by limited mobility, decreased physical endurance and social, academic or job discrimination.
Preconception and Prenatal Nursing Care Perinatal care of an obese woman requires teamwork, early planning and intervention, and effective communication to prevent complications and facilitate positive birth outcomes. Consistent care by the same health care providers throughout the course of pregnancy promotes a trusting relationship between the woman and her providers. Seeing the same provider for prenatal visits maximizes communication and allows follow-through on measures to manage weight, diet and any existing complications. The preconception period is the ideal time for the health care provider to address weight management issues for women considering pregnancy. Dieting, surgical procedures, exercise programs, pharmacotherapeutic regimes and stabilization of coexisting medical problems are more safely accomplished prior to the presence of a fetus. The height and weight of a woman before pregnancy and her exiting stores of micronu-
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trients affect the health and size of her newborn (Reifsnider & Gill, 2000). Weight loss should be carefully monitored by a registered dietician, and any medications used for weight loss must be evaluated for their effect on other drugs a woman may be taking for medical conditions. Bariatric (gastric bypass) surgery is an extreme but effective tool to assist morbidly obese women with weight loss. Women who are extremely overweight are often infertile or considered very high risk should they become pregnant. Wittgrove, Jester, Wittgrove, and Clark (1998) determined that this procedure was safe and effective in improving birth outcomes in women with excessive weight problems. This procedure should be done 12 to 15 months prior to attempting pregnancy, and vitamin/mineral supplementation is essential for positive fetal and neonatal outcomes. Assessment of overweight patients must be thorough and repeated at all prenatal exams to optimize organ system function. A thorough history must be obtained at the first prenatal visit. All medications a woman is taking for pre-existing medical conditions should be reviewed for safety and suitability during pregnancy. Because of the high incidence of diabetes in this population, a one-hour glucose challenge test should be performed at the first prenatal visit. Women diagnosed with diabetes should be instructed to maintain a fasting blood sugar level between 70 and 95 mg/dL and a two-hour postprandial blood sugar level below 120 mg/dL (Weiss & Malone, 2001). A consult with a diabetes educator is highly recommended if a woman is newly diagnosed with diabetes, has had gestational diabetes with previous pregnancies or has had the disorder for some time. Maintaining blood sugar within recommended ranges, particularly during the first trimester, is the single most important factor in preventing fetal and neonatal complications and anomalies. To address the possibility of hypertension in an obese woman, serial blood pressure measurements should be taken with an appropriately sized cuff. A cuff that is too small results in a falsely elevated blood pressure reading. A woman should be placed in an appropriate position, such as sitting, when monitoring the blood pressure. If an antepartum woman has an elevated blood pressure, raising an arm above the level of
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the heart, such as when the woman is lying on her left side and the right arm is used to measure her blood pressure, may lower the reading by as much as 20 mm Hg (Olds et al., 2000). This helps to distinguish chronic hypertension from pregnancyinduced hypertension. Consistent use of the same equipment, position and provider will enhance the accuracy of serial blood pressure measurements. Serial ultrasound examinations of an obese pregnant woman should begin in the first trimester. This is necessary to accurately date the pregnancy because many obese women have irregular, anovulatory menstrual cycles making date of last menstrual period an insufficient mechanism to calculate EDC (Weiss & Malone, 2001). As the pregnancy progresses, ultrasound may be used to evaluate fetal anatomy as this group has a higher rate of fetal anomalies, as well as determine fetal weight and growth patterns. Prenatal nutrition is of utmost concern for a woman who is overweight during pregnancy. It’s currently recommended that a women of normal weight should gain 25 to 35 pounds during pregnancy, with the average woman gaining 32 pounds (Bracero & Byrne, 1998). The weight gain of a pregnant, obese woman varies greatly, with the average weight gain being 21 pounds. Approximately 11 percent of obese patients either lose weight or have no weight gain during pregnancy (Lederman, 2001; Muscati, Graydonald, & Koski, 1996). These women are at increased risk of delivering small-for-gestationalage newborns (Reifsnider & Gill, 2000). Vitamin and mineral supplementation is essential and should include adequate iron, folic acid and calcium. Late in pregnancy, nurses might consider setting up an anesthesia consultation for an obese pregnant woman because macrosomia, fetal anomalies and ineffectual labor patterns put these women at increased risk for cesarean birth.
Nursing Care During labor, a woman with increased adipose tissue is difficult to monitor. External fetal monitoring may require one-toone care to allow the nurse to sit at the bedside and hold the transducer in a position to obtain an adequate fetal heart rate tracing. Palpation of fetal position and uterine contraction intensity may also be compromised by excessive adipose tissue.
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Bedside ultrasound devices and nurses with special ultrasound training can optimize assessment of fetal position and labor progress. As labor progresses, internal monitoring will provide a more accurate picture of the uterine contraction pattern and the fetal heart rate. To ensure appropriate monitoring of cardiovascular and respiratory status, continuous labor care by the same nurse is also recommended. Serial blood pressures taken manually provide the most accurate readings. Attention should be given to the cuff size and the woman’s position as described previously. An upright or semi-Fowler position generally facilitates lung expansion and comfort. The use of pulse oximetry will alert the nurse of early indications of maternal hypoxemia thus enabling early intervention to prevent fetal compromise. Caring for morbidly obese women in labor should be conducted in a facility capable of placing an arterial line to monitor pressures and serial blood gases should the need arise. If hypertension worsens during labor, magnesium sulfate administration and other modes of antihypertensive therapy should be anticipated. Strict monitoring of intake and output is critical in the prevention of fluid overload. To individualize the care of each woman, attention should be given to coexisting medical conditions and psychosocial needs. Monitoring blood glucose levels and administering medications throughout the labor process is essential to meeting each woman’s unique needs. IV access and blood draws are more difficult when a woman is obese, and a team of individuals with this expertise should be alerted. A matter-of-fact approach to special accommodations— such as a larger bed or wheelchair—promotes self-esteem and psychological well-being in patients who are sensitive about their special needs. Be familiar with the weight limits of operating tables and birthing beds and have a plan for securing medical equipment should a woman exceed that weight limit. A woman with low self-esteem requires support and positive feedback from the primary health care provider (Sauer, 1992). In the postpartum period, nursing care measures should be taken to prevent thrombus formation and pulmonary embolism. These measures include pneumatic compression devices applied to the lower extremities, subcutaneous heparin therapy and early ambulation. Obese postpartum patients are also at a higher risk for postpartum hemorrhage, endometritis, wound infection and wound dehiscence, and should be assessed carefully and frequently for these conditions. Women who have had a cesarean birth are likely to have a JacksonPratt drain in place, and prophylactic antibiotics should be anticipated (Weiss & Malone, 2001). It’s recommended that dietary and other weight management regimes continue during the postpartum period (Crowell, 1995). However, new or more stringent efforts should not be undertaken until the infant is at least three weeks old to allow for maternal healing (see Box 2 for dietary
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resources). If a woman chooses to breastfeed her newborn, caloric, exercise and pharmacologic therapies must be evaluated to promote weight loss while maintaining adequate infant growth patterns (Dewey, 1998; McCrory, 2000, 2001). Women choosing to try a vegetarian diet as a postpartal weight loss strategy can do so safely with adequate guidance from an experienced dietician (Mangels, 1997).
Box 2.
Getting All the Facts • American Dietetic Association: www.eatright.org • Nutrition & Your Health: Dietary Guidelines for All Americans: www.health.gov/dietaryguidelines • National Institutes of Health’s HealthFinder: www.healthfinder.gov • The Surgeon General on Obesity: www.surgeongeneral.gov/topics/obesity
References Allison, D. B., Kaprio, J., Korkeila, M., Koskenvuo, M., Neale, M. C., & Hayakawa, K. (1996). The heritability of body mass index among an international sample of monozygotic twins reared apart. International Journal of Obesity Related Metabolic Disorders, 20, 501-506. Bowers, D., & Cohen, W. (1999). Obesity and related pregnancy complications in an inner-city clinic. Journal of Perinatology, 19, 216-219. Bracero, L., & Byrne, D. (1998). Optimal weight gain during singleton pregnancy. Gynecologic and Obstetric Investigation, 46(1), 9-16. Crowell, D. (1995). Weight change in the postpartum period: A review of the literature. Journal of Nurse Midwifery, 40, 418-423. Dewey, K. (1998). Effects of maternal caloric restriction and exercise during lactation. Journal of Nutrition, 128(2), 3865-3895. Dye, T., Knox, K., Artal, R., Aubry, R., & Wojtowycz, M. (1997). Physical activity, obesity, and diabetes in pregnancy. American Journal of Epidemiology, 146(11), 961-965. Edwards, L., Hellerstedt, W., Alton, I., Story, M., & Himes, J. (1996). Pregnancy complications and birth outcomes in obese and normal-weight women: Effects of gestational weight changes. Obstetrics and Gynecology, 87(3), 389-394. Garbaciak, J., Richter, M., Miller, S., & Barton, J. (1985). Maternal weight and pregnancy complications. American Journal of Obstetrics and Gynecology, 152, 238-245. Gross, T., Solcol, R., & King, K. (1980). Obesity in pregnancy: risks and outcome. Obstetrics and Gynecology, 56, 446-450. Heard, D. (2000). Obesity. Retrieved May 23, 2002, from http://www.sh.lsumc.edu/fammed/OutpatientManual/ Obesity.htm Heit, J., O’Fallon, W., Petterson, T., Lohse, C., Silverstein, M., Mohr, D., et al. (2002). Relative impact of risk factors for deep vein thrombosis and pulmonary embolism: A
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population-based study. Archives of Internal Medicine, 162, 1182-1189. Hood, D., & Dewan, D. (1993). Anesthetic and obstetric outcome in morbidly obese parturients. Anesthesiology, 79, 1210-1218. Hora, S., & Fraser, R. (2000). A longitudinal study of maternal anthropometric changes in normal weight, overweight and obese women during pregnancy and postpartum. British Journal of Nutrition, 84(1), 95-101. Isaacs, J. D., Magann, E. F., Martin, R. W., Chauhan, S. P., & Morrison, J. C. (1994). Obstetric challenges of massive obesity complicating pregnancy. Journal of Perinatology, 14, 10-14. Jung, R. (1997). Obesity as a disease. British Medical Bulletin, 53, 307-321. Kaiser, P., & Kirby, R. (2001). Obesity as a risk factor for cesarean in a low-risk population. Obstetrics and Gynecology, 97(1), 39-43. Kalra, S., Dube, M., Pu, S., Xu, B., Tamas, L., & Horvath, S. (1999). Interacting appetite-regulating pathways in the hypothalamic regulation of body weight. Endocrine Reviews, 20(1), 68-100. Kuczmarski, R., Flegal, K., Campbell, S., & Johnson, C. (1994). Increasing prevalence of overweight among US adults: The National Health and Nutrition Examination Surveys, 1960 to 1991. Journal of the American Medical Association, 272, 205-211. Lederman, S. (2001). Pregnancy weight gain and postpartum loss: Avoiding obesity while optimizing the growth and development of the fetus. Journal of the American Medical Women’s Association, 56(2), 53-58. Lefcourt, L., & Rodis, J. (1996). Obstructive sleep apnea in pregnancy. Obstetrical and Gynecological Survey, 51, 503-506. Lewis, D., Chesson, A., Edwards, M., et al. (1998). Obstructive sleep apnea in pregnancy resulting in pulmonary hypertension. Southern Medical Journal, 1, 761-762. Mangels, A. (1997). Vegetarian nutrition during pregnancy and lactation. Perinatal Nutrition Report, 4(1), 12. Manzar, S. (2000). Effect of maternal size on neonatal glucose homeostasis. Neonatal Intensive Care, 13(5), 12, 20. McCrory, M. (2000). The role of diet and exercise in postpartum weight management. Nutrition Today, 35, 175-182. McCrory, M. (2001). Does dieting during lactation put infant growth at risk? Nutrition Reviews, 59(1), 18-21. Mokdad, A., Serdula, M., Dietz, W., Bowman, B., Marks, J., & Koplan, J. (1999). The spread of the obesity epidemic in the U.S., 1991-1998. Journal of the American Medical Association, 282, 1519-1522. Muscati, S., Graydonald, K., & Koski, K. (1996). Timing of weight gain during pregnancy, promoting fetal growth and minimizing maternal weight retention. International Journal of Obesity Related Metabolic Disorders, 20, 526-532. National Institutes of Health. (1998). Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults—The evidence report. Obesity Research (supplement), 2, 51S-209S.
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Olds, S., London, M., & Ladewig, P. (2000). Maternal-newborn nursing: A family and community-based approach (6th ed.). Upper Saddle River, NJ: Prentice Hall Health. Perlow, J., & Morgan, M. (1994). Massive maternal obesity and perioperative cesarean morbidity. American Journal of Obstetrics and Gynecology, 170, 560-565. Reifsnider, E., & Gill, S. (2000). Nutrition for the childbearing years. Journal of Obstetric, Gynecologic, and Neonatal Nursing, 29, 43-55. Rossner, S. (1998). Obesity and pregnancy. In G. Bray, C. Bouchard, & E. James (Eds.), Handbook of obesity (pp. 775-790). New York: Marcel Dekker. Ruge, S., & Andersen, T. (1985). Obstetric risks in obesity: An analysis of the literature. Obstetrical and Gynecological Survey, 40, 57-60. Sauer, A. (1992). Morbid obesity. In D. Angelini & C. Knapp (Eds.), Case studies in perinatal nursing (pp. 57-67). Gaithersburg, MD: Aspen. Scieve, L., Cogswell, M., & Scanlon, K. (1998). An empiric evaluation of the Institute of Medicine’s pregnancy weight gain guidelines by race. Obstetrics and Gynecology, 91(6), 878-884. Steinfeld, J., Valentine, S., Lerer, T., Ingardia, C., Wax, J., & Curry, S. (2000). Obesity-related complications of pregnancy vary by race. Journal of Maternal-Fetal Medicine, 9(4), 238-241. Stunkard, A., Foch, T., & Hrubec, Z. (1986a). A twin study of human obesity. Journal of the American Medical Association, 256, 51-54. Stunkard, A., Harris, J., Pedersen, N., & McClearn, G. (1990). The body-mass index of twins who have been reared apart. New England Journal of Medicine, 322, 1483-1487. Stunkard, A., et al. (1986b). An adoption study of human obesity. New England Journal of Medicine, 314, 193-198. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention. (1999). Overweight prevalence. Retrieved May 24, 2002, from http://www. cdc.gov/nchs/fastats/overwt.htm Vogler, G. P., Sorensen, T. I., Stunkard, A. J., Srinivasan, M. R., & Rao, D. C. (1995). Influences of genes and shared family environment on adult body mass index assessed in an adoption study by a comprehensive path model. International Journal of Obesity Related Metabolic Disorders, 19, 40-45. Wang, J., Davies, M., & Norman, R. (2000). Body mass and probability of pregnancy during assisted reproduction treatment: Retrospective study. British Medical Journal, 321(7272), 1320-1321. Warner, J. (2002). Obesity health costs outweigh smoking: Your health (and pocketbook) pays the price for extra pounds. Retrieved March 31, 2002, from WebMD Medical News: http://health.netscape.com/health/ nutrition/main.tmpl Weiss, J., & Malone F. (2001). Caring for obese obstetric patient. Contemporary OB/GYN, 46(6), 12-14, 16, 19-20, 23, 26. Wittgrove, A., Jester, L., Wittgrove, P., & Clark, W. (1998). Pregnancy following gastric bypass for morbid obesity. Obesity Surgery, 8, 461-463.
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nurse needs to know.
O
besity has become an epidemic in America, and most experts consider it an obstetric hazard. It coexists with and is perceived to be the cause of many forms of obstetrical and neonatal morbidity or mortality and, as a result, has an enormous impact on the health of women and their children. Experts at the U.S. Department of Health and Human Services, Centers for Disease Control and Prevention (1999) report that 61 percent of U.S. adults and almost 20 percent of U.S. adolescents of childbearing age (12 to 19 years) are overweight or obese. Obesity affects all organ systems; excessive weight contributes to a multitude of physiological complications that include, but are not limited to (Edwards, Hellerstedt, Alton, Story, & Himes, 1996; Garbaciak,
Richter, Miller, & Barton, 1985; Gross, Solcol, & King, 1980; Jung, 1997; Kaiser & Kirby, 2001; Steinfeld et al., 2000; Wang, Davies, & Norman, 2000), • • • • • • • • • • •
hypertension vascular disease diabetes birth trauma infertility hemorrhage respiratory difficulty musculoskeletal strain cancer birth defects higher rates of cesarean section
Neonatal complications may also be related to maternal size (Manzar, 2000). Psychosocial problems associated with obesity include depression, poor self-esteem and social discrimination. Obesity increases the risk of lifelong medical conditions more than smoking or alcohol abuse (Warner, 2002). Obese women are at high risk for childbearing complications and require vigilant nursing assessment and care throughout pregnancy and birth. As the epidemic of obesity increases in America, nurses will care for greater numbers of obese women. Being prepared to aggressively manage the special needs of these women and their infants will promote positive birth outcomes for these childbearing families.
Pacific nations, feminine obesity is seen as a positive physical attribute and thought to increase the value of the woman as a mate and childbearer (Scieve, Cogswell, & Scanlon, 1998). In North America, more poor women are obese than are middleclass or wealthy women (Sauer, 1992). Endocrine disorders most commonly cited as playing a role in obesity during pregnancy are thyroid and pancreatic dysfunction. Pregnant patients are routinely screened for these disorders. Thyroid problems account for less than 1 percent of maternal obesity (Heard, 2000) while pancreatic dysfunction as gestational diabetes is estimated to occur in 6 percent of all pregnancies (Olds, London, & Ladewig, 2000).
Exploring Obesity
Defining & Tracking Obesity
Obesity is a multifactorial condition with genetic, neurologic, behavioral, sociologic and/or endocrinologic components (Heard, 2000). While adipose tissue is necessary for metabolic function, obesity is an excess of body fat that results in increases in both size and number of fat cells in the body. The genetic basis for obesity is a widely accepted and a well-documented contributor to this condition. Twin studies indicate that monozygotic twins are more likely to demonstrate similar weight gain patterns than dizygotic twins (Allison et al., 1996; Stunkard, Foch, & Hrubec, 1986; Stunkard, Harris, Pedersen, & McClearn, 1990). In addition, studies of adopted children indicate that a child is more likely to be of similar weight distribution of the genetic parents than of the adoptive parents (Stunkard et al., 1986a, 1986b; Vogler, Sorensen, Stunkard, Srinivasan, & Rao, 1995). While obesity and its associated risks cross all ethnic and social strata, the incidence for black women is twice as high as it is for white women (Kaiser & Kirby, 2001; Kuczmarski, Flegal, Campbell, & Johnson, 1994). Neurologically, certain lesions in the hypothalamus can provoke hyperphagia and lead to obesity. There is also evidence linking particular neurotransmitters such as serotonin and the catecholamines to satiety (Kalra et al., 1999). When there is an interruption in the neurotransmission of these chemicals, there is an increase in appetite that may result in a person gaining excessive weight. A wide variety of sociologic and behavioral factors have been implicated in obesity. Learned dietary habits during childhood, using food as a reward or as an aid to manage stress or depression, larger portions of high-fat foods being served in American restaurants, night eating, and sedentary lifestyle are just a few of the factors leading to an overweight society (Jung, 1997). Obesity in Western society is unlike many other societies throughout the world where obesity is associated with wealth and a high level of social status. In the Far East and
A wide variety of definitions are used in the literature to define obesity, making it difficult to compare studies on this topic. The three most common ways used to describe obesity in health-related journals include (Weiss & Malone, 2001),
Sandra K. Cesario, RNC, PhD, is assistant professor in the College of Nursing at Texas Woman’s University–Houston Center. DOI: 10.1177/1091592303253864
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• the percentage of ideal body weight • body mass index (BMI) • absolute body weight Being obese can also be determined by (Bowers & Cohen, 1999), • having a pre-pregnancy or pregnancy weight of more than 200 pounds (more than 90 kg) • being greater than 110 percent of ideal body weight at the first prenatal visit • having a BMI greater than 30 Also, many authors use additional descriptive terminology to delineate degrees of obesity. Terms used in association with “obese” include slightly, moderately, massively, morbidly, markedly or grotesquely. The specific definitions of each of these terms vary among studies. The incidence of obesity has been steadily increasing worldwide. The World Health Organization considers obesity a global epidemic and public health problem as more nations become “Westernized” (Warner, 2002). Worldwide, the prevalence of obesity has increased by more than 8 percent during a 15-year period (Mokdad et al., 1999). In the U.S., the average American gains an average of one pound per year after the age of 25. Because muscle and bone mass decrease with age, the percentage of body fat becomes exaggerated. As such, Americans typically add more than 37 pounds of fat to their bodies by the time they reach age 55 (Warner, 2002). Although obesity is more prevalent in lower socioeconomic groups in the U.S., its incidence appears to be increasing in young adults with a college education (Kuczmarski et al., 1994; Mokdad et al., 1999). African American women are more overweight than Caucasian women, but African American men
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Body Mass Index (BMI) is the most common single tool used in determining obesity (see Box 1, “Gauging BMI”). BMI is a weight-to-height ratio calculation that can be determined by dividing a woman’s weight in kilograms by her height in meters squared. BMI may also be calculated by weight in pounds divided by the height in inches squared, multiplied by 704.5. Pre-printed charts are widely available to determine BMI. Experts at the Centers for Disease Control and Prevention categorize BMI as follows: • • • •
Box 1.
underweight: less than 18.5 healthy weight: 18.5 to 24.9 overweight: 25 to 29.9 obese: 30 or higher
Hip-to-waist ratio or skin-fold determinations more accurately assess the percentage of body fat. Densitometry, ultrasound and CAT scans have also been used to assess distribution of adipose tissue (Heard, 2000).
Gauging BMI Use these handy resources for fingertip information regarding obesity and body mass index calculations: • BMI Calculator for Palm OS: http://hin.nhlbi.nih.gov/bmi_palm.htm • Obesity Guidelines for Palm OS: http://hin.nhlbi.nih.gov/obgdpalm.htm • Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults: http://www.nhlbi.nih.gov/guidelines/obesity/ ob_home.htm
weigh less than Caucasian men. Hispanic women and men are more likely to weigh more than their Caucasian counterparts (Steinfeld et al., 2000). In men, BMI tends to increase until it plateaus around age 50. In women, this plateau does not occur until age 70. The three high-risk periods for weight gain in women are • at the onset of menstruation • after pregnancy • after menopause
Assessing Risk Both pregnancy and obesity are associated with distinct physiologic alterations that accentuate each other, making assessing, diagnosing and providing care for an obese pregnant woman complex and challenging (Sauer, 1992). In most cases, visual inspection of the patient provides sufficient information to elicit further investigation of weight gain pattern. Obtaining a family and individual history of body weight patterns is helpful in predicting the patient’s growth curve. Carefully maintaining weight and height graphs is essential.
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Pathophysiologic Changes Related to Obesity Most antenatal problems are due to medical conditions that often coexist with obesity. Hypertension, diabetes, pyelonephritis and obstructive sleep apnea occur quite frequently and complicate the care of pregnant women. As many as 40 percent of obese women have chronic hypertension (Ruge & Andersen, 1985; Weiss & Malone, 2001), and another 27 to 38 percent of obese women will develop pregnancy-induced hypertension (Isaacs, Magann, Martin, Chauhan, & Morrison, 1994; Rossner, 1998). Both pregnancy and obesity increase cardiac workload and myocardial oxygen consumption. Cardiac output in an uncomplicated pregnancy increases by 35 to 40 percent; in an obese woman, it increases by 50 percent. A higher left ventricular preload may lead to increased edema. Obesity hypoventilation or “Picwickian Syndrome” (named in reference to the Dickens character, Fat Joe, in the “Pickwick Papers”) might be suspected if a woman complains of sleepiness during the day, snoring or waking frequently during the night (Sauer, 1992). This condition may lead to pulmonary hypertension and may be fatal if left untreated. An increase in body weight also places excessive strain on the musculoskeletal system. Lumbar lordosis, normally present in all pregnancies to provide balance as the uterus enlarges, is exaggerated by obesity. An obese pregnant woman also may develop a thoracic kyphosis. Excessive weight increases the work of the back and leg muscles and may result in backache, leg pain, increased fatigue and aggravated varices. Skeletal changes in addition to the weight of the chest wall, breasts and viscera increase respiratory workload and lower oxygen saturation. An obese woman also may have a reduced carbon dioxide response, leading to an increased risk of
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hypoxemia with the administration of drugs that depress respiration such as narcotics and sedatives (Sauer, 1992). The incidence of obstructive sleep apnea is pronounced in this population as body weight exerts pressure on the diaphragm and airway when such a person is in a supine position (Lefcourt & Rodis, 1996; Lewis et al., 1998). These women are also at increased risk of developing hiatal hernia and markedly elevated gastric emptying times. Antenatal urinary tract infections, often resulting in pyelonephritis, occur more frequently in obese pregnant women. Diabetes is more prevalent when pregnancy and obesity coexist. Up to 19 percent of obese pregnant women have pregestational diabetes, and another 8 percent develop gestational onset diabetes (National Institutes of Health, 1998). With diabetes, the pancreas doesn’t produce sufficient insulin for carbohydrate metabolism. Cells become energy depleted while the blood glucose level remains elevated. These changes contribute to a higher incidence of (Dye, Knox, Artal, Aubry, & Wojtowycz, 1997; Edwards et al., 1996), • • • • • •
hydramnios hypertension hyperglycemia fetal macrosomia intrauterine growth retardation congenital malformations
Central fat deposition provokes more disordered glucose tolerance than peripheral fat distribution (Hora & Fraser, 2000). Obesity and adult onset diabetes are risk factors for venous thromboembolism (VTE). Adults with a BMI of at least 40 are nearly three times more likely to develop VTE than adults with a BMI of less than 25. Adults with diabetes are nearly twice as likely as persons with normal fasting glucose levels to be diagnosed with VTE (Heit et al., 2002). Complications experienced during the intrapartum period are markedly increased when the laboring woman is obese. Women in this group experience up to 55 percent more of the following complications (Kaiser & Kirby, 2001): • • • •
cesarean delivery shoulder dystocia blood loss anesthesia difficulties
Higher cesarean delivery rates are associated with fetal macrosomia and soft tissue dystocia. In addition, cesarean delivery is often complicated by excessive operative blood loss (greater than 1,000 cc’s), difficult intubations and operative times greater than two hours (Perlow & Morgan, 1994; Weiss & Malone, 2001). Vaginal birth in this group is complicated by a 30 percent rate of fetal macrosomia contributing to dysfunctional labor patterns, prolonged labor, perineal and bladder trauma and shoulder dystocia. Epidural anesthesia is more difficult to initiate and
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maintain when a woman is overweight, often requiring repeated placements of the epidural catheter to achieve success (Hood & Dewan, 1993). Assessment of the fetus and labor progress via electronic monitoring or palpation may also be difficult due to the thick layer of adipose tissue covering the uterus. Complications of obesity extend also into the postpartum period. Excessive postpartum bleeding occurs more often and may be related to decreased muscle tone, inability to palpate the fundus, macrosomia and decreased physical activity (Edwards et al., 1996). Obese women also experience increased incidence of postoperative wound infection, dehiscence and delayed healing. Endometriosis, occurring at a rate of 45 percent, complicates the postpartum course in women weighing more than 300 pounds (Bowers & Cohen, 1999). Deep vein thrombosis and pulmonary embolism occur more frequently when a postpartum woman is overweight. Many other complications are more prevalent with obesity and should be kept in mind when individualizing care for a pregnant, obese woman. Overweight and obesity are associated with an increased risk for some types of cancer, including, • • • • •
endometrial colon gallbladder kidney postmenopausal breast cancer
The risk for developing arthritis increases by 9 to 13 percent for every two-pound increase in weight. Gall bladder disease, incontinence and depression are more common. Quality of life and an ability to parent may be affected by limited mobility, decreased physical endurance and social, academic or job discrimination.
Preconception and Prenatal Nursing Care Perinatal care of an obese woman requires teamwork, early planning and intervention, and effective communication to prevent complications and facilitate positive birth outcomes. Consistent care by the same health care providers throughout the course of pregnancy promotes a trusting relationship between the woman and her providers. Seeing the same provider for prenatal visits maximizes communication and allows follow-through on measures to manage weight, diet and any existing complications. The preconception period is the ideal time for the health care provider to address weight management issues for women considering pregnancy. Dieting, surgical procedures, exercise programs, pharmacotherapeutic regimes and stabilization of coexisting medical problems are more safely accomplished prior to the presence of a fetus. The height and weight of a woman before pregnancy and her exiting stores of micronu-
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trients affect the health and size of her newborn (Reifsnider & Gill, 2000). Weight loss should be carefully monitored by a registered dietician, and any medications used for weight loss must be evaluated for their effect on other drugs a woman may be taking for medical conditions. Bariatric (gastric bypass) surgery is an extreme but effective tool to assist morbidly obese women with weight loss. Women who are extremely overweight are often infertile or considered very high risk should they become pregnant. Wittgrove, Jester, Wittgrove, and Clark (1998) determined that this procedure was safe and effective in improving birth outcomes in women with excessive weight problems. This procedure should be done 12 to 15 months prior to attempting pregnancy, and vitamin/mineral supplementation is essential for positive fetal and neonatal outcomes. Assessment of overweight patients must be thorough and repeated at all prenatal exams to optimize organ system function. A thorough history must be obtained at the first prenatal visit. All medications a woman is taking for pre-existing medical conditions should be reviewed for safety and suitability during pregnancy. Because of the high incidence of diabetes in this population, a one-hour glucose challenge test should be performed at the first prenatal visit. Women diagnosed with diabetes should be instructed to maintain a fasting blood sugar level between 70 and 95 mg/dL and a two-hour postprandial blood sugar level below 120 mg/dL (Weiss & Malone, 2001). A consult with a diabetes educator is highly recommended if a woman is newly diagnosed with diabetes, has had gestational diabetes with previous pregnancies or has had the disorder for some time. Maintaining blood sugar within recommended ranges, particularly during the first trimester, is the single most important factor in preventing fetal and neonatal complications and anomalies. To address the possibility of hypertension in an obese woman, serial blood pressure measurements should be taken with an appropriately sized cuff. A cuff that is too small results in a falsely elevated blood pressure reading. A woman should be placed in an appropriate position, such as sitting, when monitoring the blood pressure. If an antepartum woman has an elevated blood pressure, raising an arm above the level of
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the heart, such as when the woman is lying on her left side and the right arm is used to measure her blood pressure, may lower the reading by as much as 20 mm Hg (Olds et al., 2000). This helps to distinguish chronic hypertension from pregnancyinduced hypertension. Consistent use of the same equipment, position and provider will enhance the accuracy of serial blood pressure measurements. Serial ultrasound examinations of an obese pregnant woman should begin in the first trimester. This is necessary to accurately date the pregnancy because many obese women have irregular, anovulatory menstrual cycles making date of last menstrual period an insufficient mechanism to calculate EDC (Weiss & Malone, 2001). As the pregnancy progresses, ultrasound may be used to evaluate fetal anatomy as this group has a higher rate of fetal anomalies, as well as determine fetal weight and growth patterns. Prenatal nutrition is of utmost concern for a woman who is overweight during pregnancy. It’s currently recommended that a women of normal weight should gain 25 to 35 pounds during pregnancy, with the average woman gaining 32 pounds (Bracero & Byrne, 1998). The weight gain of a pregnant, obese woman varies greatly, with the average weight gain being 21 pounds. Approximately 11 percent of obese patients either lose weight or have no weight gain during pregnancy (Lederman, 2001; Muscati, Graydonald, & Koski, 1996). These women are at increased risk of delivering small-for-gestationalage newborns (Reifsnider & Gill, 2000). Vitamin and mineral supplementation is essential and should include adequate iron, folic acid and calcium. Late in pregnancy, nurses might consider setting up an anesthesia consultation for an obese pregnant woman because macrosomia, fetal anomalies and ineffectual labor patterns put these women at increased risk for cesarean birth.
Nursing Care During labor, a woman with increased adipose tissue is difficult to monitor. External fetal monitoring may require one-toone care to allow the nurse to sit at the bedside and hold the transducer in a position to obtain an adequate fetal heart rate tracing. Palpation of fetal position and uterine contraction intensity may also be compromised by excessive adipose tissue.
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Bedside ultrasound devices and nurses with special ultrasound training can optimize assessment of fetal position and labor progress. As labor progresses, internal monitoring will provide a more accurate picture of the uterine contraction pattern and the fetal heart rate. To ensure appropriate monitoring of cardiovascular and respiratory status, continuous labor care by the same nurse is also recommended. Serial blood pressures taken manually provide the most accurate readings. Attention should be given to the cuff size and the woman’s position as described previously. An upright or semi-Fowler position generally facilitates lung expansion and comfort. The use of pulse oximetry will alert the nurse of early indications of maternal hypoxemia thus enabling early intervention to prevent fetal compromise. Caring for morbidly obese women in labor should be conducted in a facility capable of placing an arterial line to monitor pressures and serial blood gases should the need arise. If hypertension worsens during labor, magnesium sulfate administration and other modes of antihypertensive therapy should be anticipated. Strict monitoring of intake and output is critical in the prevention of fluid overload. To individualize the care of each woman, attention should be given to coexisting medical conditions and psychosocial needs. Monitoring blood glucose levels and administering medications throughout the labor process is essential to meeting each woman’s unique needs. IV access and blood draws are more difficult when a woman is obese, and a team of individuals with this expertise should be alerted. A matter-of-fact approach to special accommodations— such as a larger bed or wheelchair—promotes self-esteem and psychological well-being in patients who are sensitive about their special needs. Be familiar with the weight limits of operating tables and birthing beds and have a plan for securing medical equipment should a woman exceed that weight limit. A woman with low self-esteem requires support and positive feedback from the primary health care provider (Sauer, 1992). In the postpartum period, nursing care measures should be taken to prevent thrombus formation and pulmonary embolism. These measures include pneumatic compression devices applied to the lower extremities, subcutaneous heparin therapy and early ambulation. Obese postpartum patients are also at a higher risk for postpartum hemorrhage, endometritis, wound infection and wound dehiscence, and should be assessed carefully and frequently for these conditions. Women who have had a cesarean birth are likely to have a JacksonPratt drain in place, and prophylactic antibiotics should be anticipated (Weiss & Malone, 2001). It’s recommended that dietary and other weight management regimes continue during the postpartum period (Crowell, 1995). However, new or more stringent efforts should not be undertaken until the infant is at least three weeks old to allow for maternal healing (see Box 2 for dietary
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resources). If a woman chooses to breastfeed her newborn, caloric, exercise and pharmacologic therapies must be evaluated to promote weight loss while maintaining adequate infant growth patterns (Dewey, 1998; McCrory, 2000, 2001). Women choosing to try a vegetarian diet as a postpartal weight loss strategy can do so safely with adequate guidance from an experienced dietician (Mangels, 1997).
Box 2.
Getting All the Facts • American Dietetic Association: www.eatright.org • Nutrition & Your Health: Dietary Guidelines for All Americans: www.health.gov/dietaryguidelines • National Institutes of Health’s HealthFinder: www.healthfinder.gov • The Surgeon General on Obesity: www.surgeongeneral.gov/topics/obesity
References Allison, D. B., Kaprio, J., Korkeila, M., Koskenvuo, M., Neale, M. C., & Hayakawa, K. (1996). The heritability of body mass index among an international sample of monozygotic twins reared apart. International Journal of Obesity Related Metabolic Disorders, 20, 501-506. Bowers, D., & Cohen, W. (1999). Obesity and related pregnancy complications in an inner-city clinic. Journal of Perinatology, 19, 216-219. Bracero, L., & Byrne, D. (1998). Optimal weight gain during singleton pregnancy. Gynecologic and Obstetric Investigation, 46(1), 9-16. Crowell, D. (1995). Weight change in the postpartum period: A review of the literature. Journal of Nurse Midwifery, 40, 418-423. Dewey, K. (1998). Effects of maternal caloric restriction and exercise during lactation. Journal of Nutrition, 128(2), 3865-3895. Dye, T., Knox, K., Artal, R., Aubry, R., & Wojtowycz, M. (1997). Physical activity, obesity, and diabetes in pregnancy. American Journal of Epidemiology, 146(11), 961-965. Edwards, L., Hellerstedt, W., Alton, I., Story, M., & Himes, J. (1996). Pregnancy complications and birth outcomes in obese and normal-weight women: Effects of gestational weight changes. Obstetrics and Gynecology, 87(3), 389-394. Garbaciak, J., Richter, M., Miller, S., & Barton, J. (1985). Maternal weight and pregnancy complications. American Journal of Obstetrics and Gynecology, 152, 238-245. Gross, T., Solcol, R., & King, K. (1980). Obesity in pregnancy: risks and outcome. Obstetrics and Gynecology, 56, 446-450. Heard, D. (2000). Obesity. Retrieved May 23, 2002, from http://www.sh.lsumc.edu/fammed/OutpatientManual/ Obesity.htm Heit, J., O’Fallon, W., Petterson, T., Lohse, C., Silverstein, M., Mohr, D., et al. (2002). Relative impact of risk factors for deep vein thrombosis and pulmonary embolism: A
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population-based study. Archives of Internal Medicine, 162, 1182-1189. Hood, D., & Dewan, D. (1993). Anesthetic and obstetric outcome in morbidly obese parturients. Anesthesiology, 79, 1210-1218. Hora, S., & Fraser, R. (2000). A longitudinal study of maternal anthropometric changes in normal weight, overweight and obese women during pregnancy and postpartum. British Journal of Nutrition, 84(1), 95-101. Isaacs, J. D., Magann, E. F., Martin, R. W., Chauhan, S. P., & Morrison, J. C. (1994). Obstetric challenges of massive obesity complicating pregnancy. Journal of Perinatology, 14, 10-14. Jung, R. (1997). Obesity as a disease. British Medical Bulletin, 53, 307-321. Kaiser, P., & Kirby, R. (2001). Obesity as a risk factor for cesarean in a low-risk population. Obstetrics and Gynecology, 97(1), 39-43. Kalra, S., Dube, M., Pu, S., Xu, B., Tamas, L., & Horvath, S. (1999). Interacting appetite-regulating pathways in the hypothalamic regulation of body weight. Endocrine Reviews, 20(1), 68-100. Kuczmarski, R., Flegal, K., Campbell, S., & Johnson, C. (1994). Increasing prevalence of overweight among US adults: The National Health and Nutrition Examination Surveys, 1960 to 1991. Journal of the American Medical Association, 272, 205-211. Lederman, S. (2001). Pregnancy weight gain and postpartum loss: Avoiding obesity while optimizing the growth and development of the fetus. Journal of the American Medical Women’s Association, 56(2), 53-58. Lefcourt, L., & Rodis, J. (1996). Obstructive sleep apnea in pregnancy. Obstetrical and Gynecological Survey, 51, 503-506. Lewis, D., Chesson, A., Edwards, M., et al. (1998). Obstructive sleep apnea in pregnancy resulting in pulmonary hypertension. Southern Medical Journal, 1, 761-762. Mangels, A. (1997). Vegetarian nutrition during pregnancy and lactation. Perinatal Nutrition Report, 4(1), 12. Manzar, S. (2000). Effect of maternal size on neonatal glucose homeostasis. Neonatal Intensive Care, 13(5), 12, 20. McCrory, M. (2000). The role of diet and exercise in postpartum weight management. Nutrition Today, 35, 175-182. McCrory, M. (2001). Does dieting during lactation put infant growth at risk? Nutrition Reviews, 59(1), 18-21. Mokdad, A., Serdula, M., Dietz, W., Bowman, B., Marks, J., & Koplan, J. (1999). The spread of the obesity epidemic in the U.S., 1991-1998. Journal of the American Medical Association, 282, 1519-1522. Muscati, S., Graydonald, K., & Koski, K. (1996). Timing of weight gain during pregnancy, promoting fetal growth and minimizing maternal weight retention. International Journal of Obesity Related Metabolic Disorders, 20, 526-532. National Institutes of Health. (1998). Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults—The evidence report. Obesity Research (supplement), 2, 51S-209S.
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Olds, S., London, M., & Ladewig, P. (2000). Maternal-newborn nursing: A family and community-based approach (6th ed.). Upper Saddle River, NJ: Prentice Hall Health. Perlow, J., & Morgan, M. (1994). Massive maternal obesity and perioperative cesarean morbidity. American Journal of Obstetrics and Gynecology, 170, 560-565. Reifsnider, E., & Gill, S. (2000). Nutrition for the childbearing years. Journal of Obstetric, Gynecologic, and Neonatal Nursing, 29, 43-55. Rossner, S. (1998). Obesity and pregnancy. In G. Bray, C. Bouchard, & E. James (Eds.), Handbook of obesity (pp. 775-790). New York: Marcel Dekker. Ruge, S., & Andersen, T. (1985). Obstetric risks in obesity: An analysis of the literature. Obstetrical and Gynecological Survey, 40, 57-60. Sauer, A. (1992). Morbid obesity. In D. Angelini & C. Knapp (Eds.), Case studies in perinatal nursing (pp. 57-67). Gaithersburg, MD: Aspen. Scieve, L., Cogswell, M., & Scanlon, K. (1998). An empiric evaluation of the Institute of Medicine’s pregnancy weight gain guidelines by race. Obstetrics and Gynecology, 91(6), 878-884. Steinfeld, J., Valentine, S., Lerer, T., Ingardia, C., Wax, J., & Curry, S. (2000). Obesity-related complications of pregnancy vary by race. Journal of Maternal-Fetal Medicine, 9(4), 238-241. Stunkard, A., Foch, T., & Hrubec, Z. (1986a). A twin study of human obesity. Journal of the American Medical Association, 256, 51-54. Stunkard, A., Harris, J., Pedersen, N., & McClearn, G. (1990). The body-mass index of twins who have been reared apart. New England Journal of Medicine, 322, 1483-1487. Stunkard, A., et al. (1986b). An adoption study of human obesity. New England Journal of Medicine, 314, 193-198. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention. (1999). Overweight prevalence. Retrieved May 24, 2002, from http://www. cdc.gov/nchs/fastats/overwt.htm Vogler, G. P., Sorensen, T. I., Stunkard, A. J., Srinivasan, M. R., & Rao, D. C. (1995). Influences of genes and shared family environment on adult body mass index assessed in an adoption study by a comprehensive path model. International Journal of Obesity Related Metabolic Disorders, 19, 40-45. Wang, J., Davies, M., & Norman, R. (2000). Body mass and probability of pregnancy during assisted reproduction treatment: Retrospective study. British Medical Journal, 321(7272), 1320-1321. Warner, J. (2002). Obesity health costs outweigh smoking: Your health (and pocketbook) pays the price for extra pounds. Retrieved March 31, 2002, from WebMD Medical News: http://health.netscape.com/health/ nutrition/main.tmpl Weiss, J., & Malone F. (2001). Caring for obese obstetric patient. Contemporary OB/GYN, 46(6), 12-14, 16, 19-20, 23, 26. Wittgrove, A., Jester, L., Wittgrove, P., & Clark, W. (1998). Pregnancy following gastric bypass for morbid obesity. Obesity Surgery, 8, 461-463.
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