Obesity during pregnancy can be associated with numerous maternal and perinatal risks. These risks may increase proportionately to the level of obesity.1,2,3 Therefore, addressing and managing these potential risk factors pose a challenge to the obstetrician and the anesthesiologist.
Obesity is a multifactor, chronic disease involving social, cultural, physiologic, metabolic, endocrine, genetic, psychological, and behavioral components, resulting in excess adipose and tissue mass.4 The modern basis of therapy for demographic determination is the body mass index (BMI) or the Quetelet index. It is measured by body weight in kilograms divided by the height in square meters (kg/m2). The standard for ideal body weight (IBW), the sex-specific desired weight for persons with small-, middle-, and large-build frames, is published in Metropolitan Life Insurance tables.5
Anorexia is defined as a BMI of less than 17.5 in both men and women.
Ideal weight is defined as a BMI of 19.1–25.8 in women and 20.7–26.4 in men.
Overweight is defined as a BMI of 27.3–32.3 in women and 27.9–31.1 in men.
Obesity is defined as a BMI of 32.4–34.9 in women and 31.2–34.9 in men.
Morbid obesity is defined as a BMI greater than 40.
Superobesity is defined as BMI greater than 50.
Obesity in pregnancy is defined as prepregnancy BMI of 30 kg/m2 or greater.6 The definition of obesity in pregnant women involves issues unique to this population because the pregnant woman’s weight increases over a relatively short interval of time, and much of this weight gain is related to accretion of matter that will be lost at delivery: the fetus, amniotic fluid, and blood.
The prevalence of obesity in reproductive-aged and pregnant women varies widely depending on the definition used, year, and characteristics of the study population but has increased in concordance with the increased prevalence of obesity in the general population.7,8 In the 2009–2010 National Health and Nutrition Examination Survey (NHANES), 31.9% of women of reproductive age (20 to 39 years old) were obese (BMI ≥ 30 kg/m2); the prevalence was highest in non-Hispanic blacks (56.2%).9 By comparison, in 1980 (before routine calculation of BMI), only 7% of women weighed over 200 pounds at their first prenatal visit.8
Regulation of appetite by the hypothalamus involves the collaboration or interaction of the satiety center in the ventromedial hypothalamic nucleus and the feeding center in the lateral hypothalamus.10 These areas involve numerous neurotransmitters and modulators that regulate appetite. Long-term signals communicating information about the energy stores and endocrine status of the body are mediated predominantly by humoral mechanisms. Short-term signals, mediated by gut hormones and neural signals from the brain and the gut, regulate meal initiation and termination10 (...