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Obesity

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Last update: 
September 21, 2009
Authors: 
Vincenzo Berghella

Key Points

- A multidisciplinary preconception approach is strongly suggested and should be considered best clinical practice for obese women contemplating pregnancy. (Tables 1-6) - Prevention rather than treatment alone is the only measure that will hopefully stop the vicious cycle of obesity. - manegemnt strategy is summarized in Table 7.

Diagnosis/definition

Obesity is defined as a body mass index (BMI) of ≥30. (table) 12 BMI is the weight in kilograms divided by the square of the height in meters (kg/m2). A BMI-based definition is an inexpensive and easy-to-perform method of screening for weight categories that may lead to health problems. BMI is strongly correlated with body fat. However, unlike more complicated methods of directly determining body fat content, the BMI is a screening tool, not a diagnostic one. For example, a lean muscular person may have a high BMI. To determine if excess weight is a health risk, a healthcare provider needs to perform further assessments which might include skin fold thickness measurements, evaluations of diet, physical activity, family history, and other appropriate health screenings.

  1. 1. NIH Publication no. 98-4083. Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults: The Evidence Report. NHLBI (National Heart, Lung, and Blood Institute); 1998.
  2. 2. Online BMI calculator: www.nhlbisupport.com/bmi

Epidemiology

Excess bodyweight is the sixth most important risk factor contributing to the overall burden of disease worldwide. WHO describes obesity as “one of the most blatantly visible, yet neglected, public-health problems that threatens to overwhelm both more and less developed countries”. The International Obesity Taskforce estimates that there are presently at least 1.1 billion overweight adults worldwide, including 312 million who are obese. At all ages and throughout the world, women are generally found to have higher mean BMI and higher rates of obesity than men for biological reasons.1 Since the mid-seventies, the prevalence of overweight and obesity in the US and many developed countries has increased sharply for both adults and children. Of adult women in the US, about 60% of women of childbearing age in 2003-2004 were identified as overweight or obese.2 In the US, the incidence of obesity increases from 30% in non-Hispanic white adults, to 37% of Mexican American adults, to 45.0% of non-Hispanic black adults. It appears that at least one third of all pregnant women in US are obese.3

  1. 1. James WPT, Jackson-Leach R., Ni Mhurchu, C. Overweight and obesity (high body mass index). In: Ezzati TM, ed. Comparative Quantification of Health Risks Global and Regional Burden of Disease Attributable to Selected Major Risk Factors. Vol 1. Geneva: World Health Organization; 2004:497-596
  2. 2. Ogden CL, Carroll MD, Curtin LR, McDowell MA, Tabak CJ, Flegal KM. Prevalence of overweight and obesity in the United States, 1999-2004. JAMA. 2006;295( 13):1549-1555.
  3. 3. King JC. Maternal obesity, metabolism, and pregnancy outcomes. Annu Rev Nutr. 2006;26:271-291.

Complications

Obesity is associated with numerous maternal and fetal/neonatal complications.(Tables 2,3,4)1 2 The medical provider should review in details all these significant risks, especially before an obese woman attempts a pregnancy. The incidence of complications is directly related to the category of BMI, e.g. the higher the BMI, the higher the incidence of complications.3 Increased BMI is a risk factor for impairment of carbohydrate tolerance. Fasting and post-prandial plasma insulin concentrations are higher in obese pregnant women than in those who are not obese. Even in overweight subjects (BMI 25-29.9) the incidence of gestational diabetes is 1.8 to 6.5 times greater than that in normal subjects, and in obese women (BMI >=30) the incidence is 1.4 to 20-fold higher than that in normal subjects.4 5 Maternal hemodynamic changes in obese gravidas include higher arterial blood pressure, hemoconcentration and altered cardiac function. Hypertensive disorders including gestational hypertension and preeclampsia are significantly more prevalent in obese pregnant women. In obese women, the incidence of hypertension is 2.2-21.4 times higher, and preeclampsia occurs 1.2-9.7 times more often than in controls. Obesity is also associated with a slightly higher risk of urinary tract infections and respiratory disorders, and places these women in a moderate risk category for the development of thromboembolic events. There is an increased incidence of major congenital malformation of 37.5% when mothers where obese compared to non-obese controls. Neural tube and cardiac defects are the most prevalent malformations in the affected fetuses. High prepregnancy BMI and excess gestational weight gain are independent risk factors for delivering large-for-gestational-age infants, as well as for undergoing operative delivery.6 The increased incidence of gestational diabetes further contributes to the risk of macrosomia, but can be modified by maintaining good glycemic control. Women with a prepregnancy BMI >30 deliver macrosomic infants 18 times more frequently than normal weight women do. Macrosomia increases the risk of shoulder dystocia, birth injury, low Apgar scores and perinatal death. Cesarean deliveries result in fewer birth injuries for macrosomic infants but the perinatal death rate remains unchanged. The risk of perinatal death has been shown to be higher in both overweight and obese gravidas. In overweight women this risk is increased up to 2.5 fold, and in obese women, up to 3.4 fold when compared to the risk in normal weight women.7 While maternal weight <50kg (<120lbs) is one of the strongest risk factors for spontaneous preterm birth, obesity is not associated with this complication, and is in fact somewhat protective. Indicated preterm birth because of maternal complications instead is more common.8 Most authors report a higher frequency of induction of labor in obese women than in normal weight women. 9 Trial of labor after a prior cesarean (TOLAC) delivery is associated with lower rates (usually about ≤50%) of vaginal birth after cesarean (VBAC) in obese women.10 The rate of cesarean delivery in obese women is consistently higher with a 1.2-3.0 fold increase over the rates in control groups. Each 1-unit increase in pregravid BMI increases the risk of cesarean delivery by 7%.11 Antepartum complications of obesity largely account for this higher cesarean delivery rate, as well as macrosomia-associated cephalopelvic disproportion, non-reassuring fetal testing, and failed induction. Operative risks are also high in obese patients, including increased total operative time, blood loss, endometritis, and wound disruptions and infections. Obese parturients therefore tend to require anesthesia more often, and are at increased risk for anesthesia-related morbidity and mortality. Regional (epidural or spinal) anesthesia is more difficult to achieve, given the changes in the anatomy of the back. Nonetheless, regional anesthesia should be attempted if at all possible, because of the increased chance of maternal mortality associated with general anesthesia in obese gravidas.12 The incidence of partially obliterated oropharyngeal anatomy among obese parturients is double that among non obese parturients. This leads to an increased risk of difficult intubation, gastric aspiration, and difficulty in maintaining adequate mask ventilation. Mask ventilation tends to be difficult because of low chest wall compliance and increased intra-abdominal pressure.13 Damaging events related to the respiratory system are significantly more common in obese parturients (32%) than in non obese parturients (7%). The problems highlight the increased need to have airway algorithms and equipment readily available when caring for these obese parturients.14 Long-term maternal complications of obesity are listed in Table 4. Among the most morbid complications are type 2 diabetes mellitus, and cardiovascular disease, and metabolic syndrome.15 16 The metabolic syndrome, or “syndrome X”, is the simultaneous findings of risk factors for both of these conditions in a given individual. The essential diagnostic criteria include some combination of the following: insulin resistance, impaired glucose tolerance, or diabetes; abdominal obesity; dyslipidemia; and hypertension. Maternal obesity, especially when associated with diabetes, predisposes infants to develop obesity (and its complications) themselves during childhood, especially in the case of high birth weight.

  1. 1. King JC. Maternal obesity, metabolism, and pregnancy outcomes. Annu Rev Nutr. 2006;26:271-291.
  2. 2. Naeye RL. Maternal body weight and pregnancy outcome. Am J Clin Nutr. 1990;52( 2):273-279.
  3. 3. Hensrud DD, Klein S. Extreme obesity: A new medical crisis in the United States. Mayo Clin Proc. 2006;81( 10 Suppl):S5-10.
  4. 4. Naeye RL. Maternal body weight and pregnancy outcome. Am J Clin Nutr. 1990;52( 2):273-279.
  5. 5. Galtier-Dereure F, Boegner C, Bringer J. Obesity and pregnancy: Complications and cost. Am J Clin Nutr. 2000;71( 5 Suppl):1242S-8S.
  6. 6. Cnattingius S, Bergstrom R, Lipworth L, Kramer MS. Prepregnancy weight and the risk of adverse pregnancy outcomes. N Engl J Med 1998;338( 3):147-152.
  7. 7. Cnattingius S, Bergstrom R, Lipworth L, Kramer MS. Prepregnancy weight and the risk of adverse pregnancy outcomes. N Engl J Med. 1998;338( 3):147-152.
  8. 8. Hendler I, Goldenberg RL, Mercer BM, et al. The preterm prediction study: Association between maternal body mass index and spontaneous and indicated preterm birth. Am J Obstet Gynecol. 2005;192( 3):882-886.
  9. 9. Yu CKH, Teoh TG, Robinson S. Obesity in pregnancy. BJOG 2006;113:1117-25.
  10. 10. Catalano PM. Management of obesity in pregnancy. Obstet Gynecol. 2007;109( 2 Pt 1):419-433.
  11. 11. Brost BC, Goldenberg RL, Mercer BM, et al. The preterm prediction study: Association of cesarean delivery with increases in maternal weight and body mass index. Am J Obstet Gynecol. 1997;177( 2):333-7; discussion 337-41.
  12. 12. Endler GC, Mariona FG, Sokol RJ, Stevenson LB. Anesthesia-related maternal mortality in Michigan, 1972 to 1984. Am J Obstet Gynecol. 1988;159( 1):187-193.
  13. 13. Ezri T, Szmuk P, Evron S, Geva D, Hagay Z, Katz J. Difficult airway in obstetric anesthesia: A review. Obstet Gynecol Surv. 2001;56( 10):631-641.
  14. 14. Chadwick. Obstetric anesthesia:Closed claims update II. Anesthesiology News [obstetric anaesthesia]. 1999;63:1-6.
  15. 15. Mokdad AH, Bowman BA, Ford ES, Vinicor F, Marks JS, Koplan JP. The continuing epidemics of obesity and diabetes in the United States. JAMA 2001;286(10):1195-1200.
  16. 16. Mokdad AH, Ford ES, Bowman BA, et al. Prevalence of obesity, diabetes, and obesity-related health risk factors, 2001. JAMA. 2003;289( 1):76-79.
Pregnancy Management

Preconception counseling

Prevention must play a key role in medical management of obesity. 1 Pregnancy (Tables 2-3) and long-term (Table 4) complications should be reviewed with the obese woman, especially preconceptionally. This counseling is aimed at a plan to avoid them though weight loss. Height and weight should be recorded for all women at each doctor visit to allow for calculation and follow-up of BMI. It’s beneficial to review the BMI category, make sure it’s understood if the BMI category is not normal (Table 1), add oral and written information regarding the complications for the woman and family to take home. Advice that weight loss will prevent complications and increase fertility should be provided. At times perception of body image, and therefore comprehension of its true consequences, are difficult to convey, with patients unwilling to accept labeling. By asking a woman whether she is concerned about her weight or if she has attempted to loose weight, the physician will be able to assess her interest in weight loss. (Table 5).2 Since obesity often tracks from childhood into adult life,3 Eriksson J, Forsen T, Osmond C, Barker D. Obesity from cradle to grave. Int J Obes Relat Metab Disord. 2003;27( 6):722-727. and there is evidence that this trend may actually begin in fetal life, preventative efforts for women of childbearing age prior to conception could have a significant effect on decreasing obesity at a population level. Infants born to mothers with a higher BMI in pregnancy demonstrate more rapid childhood growth and an increased risk of becoming obese in adult life. A rapid childhood weight gain is associated with an increased risk of type II diabetes and cardiovascular disease,4 and the age of onset of these conditions is significantly earlier in those who become obese in childhood. For all these reasons the preconception visit may be the single most important health care visit when viewed in the context of its effect on pregnancy. One of the major obstacles in dealing with obesity is the uncomfortable feeling reported by physicians in addressing the problem and its solutions with overweight and obese patients. This reluctance by physicians to address the problem results in lost opportunities for patient education and prevention.5 At the first encounter with the patient her BMI should be calculated, and recommendations for achieving a BMI of 20-25 should be discussed. A thorough review of the patient’s medical history, paying special attention to the presence of co-morbid conditions including diabetes, chronic hypertension, thyroid disease, cardiovascular, renal and respiratory diseases is essential. Evaluation for evidence of complications or end organ damage related to co-morbid conditions is indicated, and the management of these conditions is optimized in preparation for conception. A review of the patient’s current medications is performed, and substitution of medications with known or suspected fetal risks for those believed to be safer in pregnancy is done whenever possible. Recently weight loss surgery is increasing in popularity as one of the most effective tools available in order to reduce body weight in morbidly obese patients. Several different types of surgical approaches are available but the most common one used in the USA in reproductive –age women is the Roux-en-Y procedure.6 There is evidence that complications of pregnancy are prevented if an obese woman undergoes bariatric surgery and reverts to a lower BMI category before she gets pregnant. In fact fertility is enhanced by reverting to lower BMI. Pregnancy should be delayed until at least 12 months post bariatric surgery, to allow for the woman to benefit from anticipated weight loss. Iron, vitamin B12, folate and calcium need to be checked and replenished as appropriate.

  1. 1. DiLillo M, Hendrix N, O’Neill M, Berghella V. Pregnancy in obese women: What you need to know. Contemporary OB GYN 2008;53 (11):48-53.
  2. 2. Wadden TA, Berkowitz RI, Vogt RA, Steen SN, Stunkard AJ, Foster GD. Lifestyle modification in the pharmacologic treatment of obesity: A pilot investigation of a potential primary care approach. Obes Res. 1997;5( 3):218-226.
  3. 3. Eriksson J, Forsen T, Tuomilehto J, Osmond C, Barker D. Size at birth, childhood growth and obesity in adult life. Int J Obes Relat Metab Disord. 2001;25( 5):735-740.
  4. 4. Forsen T, Eriksson J, Tuomilehto J, Reunanen A, Osmond C, Barker D. The fetal and childhood growth of persons who develop type 2 diabetes. Ann Intern Med. 2000;133( 3):176-182.
  5. 5. Power ML, Cogswell ME, Schulkin J. Obesity prevention and treatment practices of U.S. obstetrician-gynecologists. Obstet Gynecol. 2006;108( 4):961-968.
  6. 6. Wax JR, Pinette MG, Ccartin A, Blackstone J. Ffemale reproductive issues following bariatric surgery. Obstet Gynecol Survey 2007;62:595-604.

Prenatal care

Height and weight should be recorded for all women at the initial prenatal visit to allow for calculation of BMI (table 1), and the category written in the record and reviewed with the patient. The obstetric complications of obesity generally refer to preconception and first trimester obesity, and not to a non-obese woman becoming obese because of excessive weight gain in pregnancy. Management of obesity during pregnancy includes avoiding excessive weight gain. At term the collective weight of fetus, placenta and amniotic fluid averages 4-5kg.1 The current recommended total weight gain in obese women is >=11lb or 5kg, (Table 6) but sufficient data show that these weight gain recommendations are excessive, since a significant portion of the weight gain in pregnancy is centrally distributed subcutaneous fat, to be avoided in obese women.2 None of the available pharmacologic or medical therapies to treat obesity are suggested during pregnancy, and significant weight loss during pregnancy is discouraged (but highly encouraged pre- and/or post-pregnancy). Appropriate maternal weight control during pregnancy not only prevents maternal, but also fetal/neonatal complications, as maternal weight gain is closely associated with macrosomia. Weight gain during pregnancy is a strong predictor of sustained weight retention, as a gain of >9Kg is correlated with greater amount of weight retained between successive pregnancies. A balanced diet, which includes high fiber and complex carbohydrates and a low glycemic intake, should be reviewed with a nutritionist. Exercise regimens should be reviewed and encouraged in order to limit weight gain. Examples of exercise are swimming, brisk walking, running, biking, or gym aerobics at least three times a week, for about 30 minutes each session. Up to 5mg of folic acid supplementation daily is recommended, since increased BMI is associated with low serum folate and obesity with NTDs. (Table 3) Excess weight has an effect on biochemical serum aneuploidy screening, so that adjustment has to be made according to maternal weight to achieve similar detection rates as in other women.3 Early glucola screening (at the first prenatal visit, preferentially in the first trimester if not already done preconceptionally) should be considered because of the high risk of pre-existing diabetes and gestational diabetes.

  1. 1. Catalano PM. Management of obesity in pregnancy. Obstet Gynecol. 2007;109( 2 Pt 1):419-433.
  2. 2. Catalano PM. Management of obesity in pregnancy. Obstet Gynecol. 2007;109( 2 Pt 1):419-433.
  3. 3. Evans MI. Harrison H. O'Brien JE. Huang X. Chervenak FA. Henry GP. Wapner RJ. Maternal weight correction for alpha-fetoprotein: mathematical truncations revisited. Genetic Testing 2002;6(3):221-3.

Antepartum testing

Given the long distance between probe and the fetus, ultrasonography for any indication is often not as accurate of a screening or diagnostic test as in non obese women.1. In addition to the first trimester dating and the second trimester anatomy ultrasounds, a fetal echocardiogram can be considered, especially for women with poorly-controlled diabetes.2 Ultrasound for fetal growth in the third trimester (e.g. around 32 weeks) may be considered especially if poorly controlled diabetes and/or macrosomia are suspected. Antepartum fetal testing is indicated even in the absence of co-morbidities given the fact that fetal death is more than twice the rate of normal controls even in obese women without medical or obstetrical complications.3

  1. 1. Dashe JS, McIntire DD, Twickler DM. Effect of maternal obesity on the ultrasound detection of anomalous fetuses. Obstet Gynecol 2009;113:1001-7.
  2. 2. Catalano PM. Management of obesity in pregnancy. Obstet Gynecol. 2007;109( 2 Pt 1):419-433.
  3. 3. Nohr EA, Bech BH, Davies MJ, Frydenberg M, Henriksen TB, Olsen J. Prepregnancy obesity and fetal death: A study within the Danish national birth cohort. Obstet Gynecol. 2005;106( 2):250-259.

Delivery

Counseling and anticipation regarding intrapartum complications (Tables 2,3) needs to be performed before labor. This also includes an anesthesia consult, especially to evaluate the airway. Consideration should be given to having a large operating table, and extra personnel. Surgical back-up and available blood products may be necessary. There is not sufficient data to assess which is the best surgical incision for cesarean in the obese gravida, as this may differ depending on the category and type (e.g. central etc) of obesity. Placing the incision above the panniculus adiposus, which at times means above the umbilicus, may be necessary in the woman with extreme obesity. The use of the Mobious retractor during cesarean delivery of obesity gravidas has been associated with no difference in operating time but improved visualization and surgeon satisfaction in the sole randomized trial on this subject.1. During cesarean delivery, the subcutaneous fat should be closed with sutures in any woman in which this thickness is >2cm.2 The obese woman considering TOLAC should be counseled regarding the lower rate of success, and balance those with the higher morbidity associated with cesarean, considering especially maternal age in regards to plan for future pregnancies. Given the higher risk of venous thromboembolism, obese gravidas should avoid at all costs prolonged bed rest, even post-operatively. Early ambulation should be encouraged. Either compression boots or prophylactic heparin should be employed at all times the woman is at bed rest, including intra- and post-operatively.

  1. 1. Moroz L, Bowers G, Hayes EJ; O’Brien J, Carroll T, Baxter JK. Self-retained vs. traditional retractors for cesarean delivery in obese women: a randomized controlled trial. AM J Obstet Gynecol 2008;111:101s
  2. 2. Berghella V, Baxter JK, Chauhan SP. Evidence-based surgery for cesarean delivery. Am J Obstet Gynecol. 2005;193( 5):1607-1617.

Anesthesia

Prenatal anesthesia consult is suggested.

Post-partum/breastfeeding

All preconception recommendations (Table 6) apply to the postpartum period. Failure to loose the weight accumulated in pregnancy and to revert to a normal BMI is associated with long-term complications (Table 4). In fact even a slight change in pre-pregnancy BMI from the first to the second pregnancy is associated with some of these complications. Weight loss, reverting to a normal BMI, through adequate diet and exercise should be encouraged, planned, if not appropriately referred, and checked long-term for success. All medical complications, most commonly diabetes and hypertension, should be managed appropriately. Women with gestational diabetes should be given after 6 weeks postpartum the 75g – 2hr test to screen for overt diabetes. When diabetes complicates the course of pregnancy, infants are predisposed to develop overweight and obesity during childhood especially in the case of high birth weight. Hypertension during pregnancy is also responsible for increased morbidity during infancy. At 6 years of age, mean diastolic blood pressure is higher in children of women who developed preeclampsia during pregnancy than in children of control subjects. Genetics factors also play an important role in the development of obesity. After delivery obese mothers are also more likely than normal weight mothers to experience urinary symptoms such as stress incontinence and urgency.

Historic notes

Hippocrates (460- 377 BC) wrote: “Corpulence is not only a disease itself, but the harbinger of others,” recognizing that obesity is a medical disorder that leads to many comorbidities. Nevertheless the problems of overweight and obesity have achieved global recognition only at the end of the XX century, in contrast to underweight, malnutrition and infectious diseases that have always dominated medicinal interest.

Tables

Patient information

Resources American Medical Association – Roadmaps for Clinical Practice series: Assessment and management of adult obesity www.ama-assn.org/ama/pub/category/10931.html American Society for Bariatric Surgery www.asbs.org ACOG Clinical Updates in Women’s Health Care-Weight control: assessment and management www.clinicalupdates.org National Heart, Lung, and Blood Institute-Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults www.nhlbi.nih.gov/guidelines/obesity/ob_home.htm The Surgeon General’s call to action to prevent and decrease overweight and obesity www.surgeongeneral.gov/topics/obesity U.S. Preventive Services Task Force-Screening for obesity in adults www.ahrq.gov/clinic/uspstf/uspobes.htm American Obesity Association www.obesity.org American Society of Bariatric Physicians www.asbp.org MedlinePlus: Weight Loss and Dieting www.nlm.nih.gov/medlineplus/weightlossanddieting.html National Heart, Lung, and Blood Institute Obesity Education Initiative www.nhlbi.nih.gov/about/oei/index.htm Overeaters Anonymous www.overeatersanonymous.org TOPS-Take Off Pounds Sensibly www.tops.org Weight-control Information Network www.win.niddk.nih.gov