Obesity
BS. Nguyễn Hồng Anh
Extensive weight gain is a major health problem today in many
auent societies. Te Centers or Disease Control and Prevention (CDC) (2020) reported the prevalence in the United
States during 2017 to 2018 to be 42 percent among all adults.
Te adverse health aspects o obesity are staggering and include
increased risks or type 2 diabetes, heart disease, hypertension,
and osteoarthritis. Importantly, obese women and their etuses
are predisposed to numerous pregnancy-related complications
and to long-term morbidity and mortality.
GENERAL CONSIDERATIONS
■ Definitions and Prevalence
O systems to classiy obesity, the body mass index (BMI), also
known as the Quetelet index, is most oten used. Te BMI is
calculated as weight in kilograms divided by the square o the
height in meters (kg/m2). Calculated BMI values are available
in various chart and graphic orms (Fig. 51-1). Te National
Institutes o Health (2000) classies adults according to BMI
as ollows: normal is 18.5 to 24.9 kg/m2, overweight is 25 to
29.9 kg/m2, and obese is ≥30 kg/m2. Obesity is urther divided
into: class 1 is 30 to 34.9 kg/m2, class 2 is 35 to 39.9 kg/m2,
and class 3 is ≥40 kg/m2. Class 3 obesity is oten reerred to
as morbid obesity, and supermorbid obesity describes a BMI
≥50 kg/m2.
Using these denitions, rom 2015 to 2016 in the United
States, among girls and women, the prevalence o obesity rose
with age and varied among ethnicities (Fig. 51-2) (Centers or
Disease Control and Prevention, 2020). Overall, severity also
advances with increasing poverty. Last, a genetic predisposition
has been identied (Locke, 2015; Shungin, 2015).
■ Adipose Patopysiology
Fat tissue is much more complex than merely its energy storage unction. Many at tissue cells communicate with all other
tissues via endocrine and paracrine actors, which are cytokines
specically termed adipokines, lipokines, and exosomal microRNAs
(Scheja, 2019). Some o these with metabolic unctions include
adiponectin, leptin, tumor necrosis actor α (NF-α), interleukin 6 (IL-6), resistin, visatin, apelin, vascular endothelial
growth actor (VEGF), lipoprotein lipase, and insulin-like
growth actor. Adiponectin is a principal adipokine. It enhances
insulin sensitivity, blocks hepatic glucose release, and has cardioprotective eects on circulating plasma lipids. An adiponectin decit is linked with diabetes, hypertension, endothelial cell
activation, and cardiovascular disease.
Cytokines that result in insulin resistance are leptin, resistin,
NF-α, and IL-6, and higher levels o these are ound during pregnancy. Indeed, adipokines, especially the inammatory
cytokines, may be the primary stimulant o insulin resistance
(Yang, 2016). Conversely, adiponectin has antiinammatory
and insulin-sensitizing roles and is negatively regulated by at
mass. Perivascular adipose tissue also serves as a signaling mediator in regulating vascular unction (Ahmadieh, 2020). Placental production o these adipokines is also important (Sartori,
2016) (Chap. 5, p. 99)
FIGURE 51-1 Chart for estimating body mass index (BMI). To find the BMI category for a particular subject, locate the point at which the
height and weight intersect.
■ Metabolic Syndrome
Given its multiaceted endocrine and paracrine unctions, the
detrimental eects o excessive adipose tissue are not surprising
(Gilmore, 2015). Obesity interacts with inherited actors to cause
insulin resistance. Tis resistance is characterized by impaired glucose metabolism and a predisposition to type 2 diabetes. Insulin
resistance also causes several subclinical abnormalities that predispose to cardiovascular disease and accelerate its onset. Te most
important among these are type 2 diabetes, dyslipidemia, and
hypertension, which are constituents o the metabolic syndrome.
Criteria to dene this syndrome are ound in Table 51-1.
Waist circumerence is the preerred measurement or screening, but any three o ve actors listed are sufcient to diagnose
the metabolic syndrome. Notably, most patients with type 2
diabetes have metabolic syndrome according to these criteria.
Also, obese women with hypertension typically demonstrate
elevated plasma insulin levels.
FIGURE 51-2 Prevalence of obesity in the United States by race:
United States 2015–2016.
Te National Health and Nutrition Examination Survey
(NHANES) o the CDC documented an overall prevalence o
34 percent or the metabolic syndrome in the United States
by 2012 (Moore, 2017). As expected, the prevalence rose with
age. It was 20 percent or those aged 18 to 29 years and was
36 percent or those aged 30 to 49 years.
■ Nonalcoolic Fatty Liver Disease
Generally speaking, visceral adiposity correlates with hepatic
at content (Cornier, 2011). With obesity, excessive at accumulates in the liver and is termed hepatic steatosis. Tis is also
called nonalcoholic fatty liver disease (NAFLD). In persons with
the metabolic syndrome, steatosis can progress to nonalcoholic
steatohepatitis (NASH) and then potentially to cirrhosis and
hepatocellular carcinoma. It is the major cause o cirrhosis and
liver cancer, and annual medical costs o NAFLD in the United
States exceed $100 billion (Diehl, 2017). Moreover, NAFLD is
strongly associated with cardiovascular disease (argher, 2016).
Tese interactions are explored urther in Chapter 58 (p. 1040).
■ Obesityassociated Morbidity
Obese individuals suer well-known consequences such as glucose intolerance, hypertension, dyslipidemia, and metabolic
syndrome. Furthermore, metabolic syndrome and obesity are
linked with cardiovascular disease, including myocardial inarction, atrial brillation, heart ailure, and stroke (Koliaki, 2019).
Excessive adiposity raises blood pressure and accounts or up
to 75 percent o primary hypertension (Hall, 2019). Insulin
resistance and metabolic syndrome cause structural cerebral
changes in the hippocampus and lower executive unctioning
and memory in adults (Kullman, 2016). And cytokine-induced
osteoarthritis has long been linked to obesity (u, 2019).
Because o the oregoing, it is not surprising that obesity is
associated with higher rates o all-cause early mortality. Cardiovascular mortality data rom 19 prospective studies are
shown in Figure 51-3 (Gonzalez, 2010). In these and other
studies, mortality risk rom cardiovascular disease and cancer
grew proportionally with increasing BMI. However, an obesity paradox—whereby certain groups actually derive a survival
advantage rom being obese—is hypothesized (Hainer, 2013).
Despite this, the health benets o weight normalization are
well documented (Cheung, 2017).
■ Obesity Treatment
Weight loss is tremendously difcult. I achieved, long-term
maintenance poses equally daunting challenges. Obstetriciangynecologists are encouraged to aid weight loss in obese adult
women. Successul approaches include behavioral, pharmacological, and surgical techniques or a combination o these (Dixon,
2016; Heymseld, 2017). Dietary changes and exercise reduce
weight and rates o the associated metabolic syndrome (Garvey,
2016; Martin, 2018). When used in conjunction with bariatric
surgery, glucose control in those with type 2 diabetes is improved.
However, both surgical and medical interventions are associated
with appreciable long-term ailure rates. Indeed, the ailure rate is
50 percent in patients with diabetes undergoing bariatric surgery
(Mingrone, 2015).
FIGURE 51-3 Estimated hazard ratios (95% CI) for death due
to cardiovascular disease according to body mass index among
1.46 million white adult men and women.
PREGNANCY AND OBESITY
Obese women unequivocally have reproductive disadvantages (Lainez, 2019). Tis translates into difculty in achieving pregnancy, early and recurrent pregnancy loss, preterm
delivery, and several obstetrical, medical, and surgical complications with pregnancy, labor, delivery, and the puerperium
(American College o Obstetricians and Gynecologists, 2021).
Also, oral contraceptive pill ailure and associated thromboembolism may be more likely. Second-trimester surgical abortion
in obese women also carries an increased complication risk
(Mark, 2018). Last, inants—and later, adult children—o
obese mothers have correspondingly higher morbidity rates
(Godrey, 2017; He, 2020).
Obesity complicating pregnancy has grown substantially in
this country. Our experiences at Parkland Hospital over three
epochs are shown in Figure 51-4. Most recently, obese women
constitute >60 percent o pregnant gravidas in our health system.
FIGURE 51-4 Increasing prevalence of obesity during four epochs
in pregnant women classified at the time of their first prenatal visit
at Parkland Hospital.
TABLE 51-2. Adverse Pregnancy Effects in Overweight and Obese Women
Maternal Morbidity
For overweight women, higher rates o adverse outcomes complicate pregnancy. Shown in Table 51-2 are results rom ve
studies including more than 1 million singleton pregnancies.
Although not as magnied as in the obese cohort, rates o
almost all complications are signicantly greater in overweight
women than in those with normal BMI.
For obese women, denitions used in studies o adverse outcomes vary widely, and BMIs rom >30 kg/m2 to >50 kg/m2
have served as thresholds (Crane, 2013; Pratt, 2020; Stamilio, 2014). In one study, Mariona (2017) reviewed maternal
deaths in Michigan and ound that the maternal mortality
rate was nearly ourold higher in obese women. Women with
supermorbid obesity experience very high rates o maternal and
neonatal complications including preeclampsia, macrosomia,
and cesarean delivery, along with higher rates o neonatal
meconium aspiration, ventilator support, and neonatal death
(Marshall, 2014; Smid, 2016). Data rom one large study are
shown in Figure 51-5 (Weiss, 2004).
Especially striking are the markedly elevated rates o hypertension and gestational diabetes. As discussed previously, obesity and the metabolic syndrome are characterized by insulin
resistance, which creates low-grade inammation, endothelial
activation, and increased sodium reabsorption (Hall, 2019).
Tese latter eects play a central role in preeclampsia (Chap.
40, p. 691). Te overwhelming association between rising
maternal BMI and the incidence o preeclampsia is depicted
in Figure 51-6 (HAPO Study Cooperative Research Group,
FIGURE 51-5 Incidence of selected pregnancy outcomes in women enrolled in the FASTER (First-and Second-Trimester Evaluation of Risk)
trial according to BMI.
FIGURE 51-6 Hyperglycemia and Adverse Pregnancy Outcome
(HAPO) study: frequency of preeclampsia according to BMI
2008). Te risks or hypertension are highest in women with
a BMI >50 kg/m2 (Pratt, 2020). Similar observations were
reported rom a large Canadian study and by the Sae Labor
Consortium (Kim, 2016; Schummers, 2015).
Obesity and hypertension are common coactors in peripartum heart ailure (Cunningham, 2012). Stewart and colleagues
(2016) used magnetic resonance imaging to prospectively
study the eect o obesity on cardiac remodeling in pregnancy.
Concentric remodeling, which was considered abnormal, was
greater in overweight or obese women (Fig. 51-7). Tis, however, regressed to normal by 3 months postpartum. riebwasser
and coworkers (2019) ound that women with abnormal cardiac remodeling had a higher incidence o pregnancy-associated
hypertensive disorders.
Obesity and gestational diabetes are inextricably linked as
shown in able 51-2. Teir coexistence and associated adverse
pregnancy outcomes are discussed in Chapter 60 (p. 1068).
Nonalcoholic atty liver disease is associated with several adverse
pregnancy outcomes (Chap. 58, p. 1040). In a cohort o women
30
20
10
2.1 2.9
4.8
8.2
12.1
23.4
30.4
0
≤23.2
23.3–26.7
26.8–30.5
30.6–33.6
33.7–38.3
38.4–44
>44
Body mass index (kg/m2)
Incidence (percent)
FIGURE 51-6 Hyperglycemia and Adverse Pregnancy Outcome
(HAPO) study: frequency of preeclampsia according to BMI.
12–16
LVM / LVEDV (g/mL)
26–30
Pregnancy (weeks)
32–36 3 mos
Postpartum
0.60
0.65
0.70
0.75
0.80
0.85
Obese
Normal-weight
FIGURE 51-7 Geometric changes of ventricular remodeling
across pregnancy in obese and normal-weight women determined
by cardiac MR imaging. LVM = left ventricular mass,
LVEDV = left ventricular end-diastolic volume.
with NAFLD, risks or preeclampsia, preterm birth, low-birthweight neonates, cesarean delivery, and gestational diabetes were
elevated (Hagström, 2016). In one prospective study o 476
pregnancies, rst-trimester sonographic evidence o maternal
NAFLD was strongly associated with gestational diabetes (De
Souza, 2016a,b). Meyer and associates (2013) ound that overweight and obese gravidas had a higher proportion o low-density
lipoprotein III (LDL-III) compared with that o normal-weight
women. LDL-III predominance is a hallmark o the ectopic liver
at accumulation that is typical o NAFLD. At Parkland Hospital, we are now requently encountering obese gravidas who have
NAFLD and evidence o steatohepatitis maniest by elevated
serum hepatic transaminase levels. In rare cases, liver biopsy is
necessary to exclude other causes or these ndings.
Quality-o-lie measures also are negatively aected by
obesity during pregnancy (Ruhstaller, 2017). One systematic
review ound signicantly higher risks o depression in overweight and obese women during and ater pregnancy (Molyneaux, 2014). Obese women were also signicantly more likely
to experience anxiety during pregnancy.
■ Perinatal Mortality
Stillbirths are more prevalent as the degree o obesity accrues
(Schummers, 2015). In a review o almost 100 studies, obesity was the highest-ranking modiable risk actor or stillbirth
(Flenady, 2011). In women with supermorbid obesity compared
with normal-weight gravidas, Yao and associates (2014) ound 5.7
and 13.6-old higher stillbirth rates at 39 and 41 weeks’ gestation,
respectively. Remarkably, 25 percent o term stillbirths in this
study involved obese women. Chronic hypertension with superimposed preeclampsia associated with obesity is one cause o excessive stillbirths. Tese etal deaths may be associated with placental
lesions o decidual arteriopathy and inarctions (Avagliano, 2020).
Evaluating perinatal death rates, Lindam and coworkers
(2016) reported that high maternal BMI in early pregnancy was
a risk actor. Te risk o neonatal death also is greater or obese
women (Johansson, 2014; Meehan, 2014). Last, one study
ound that accruing weight between pregnancies is a risk actor
or perinatal mortality, whereas weight loss between pregnancies or overweight women lowers this risk (Cnattingius, 2016).
■ Perinatal Morbidity
Both etal and neonatal complication rates are increased in obese
women. wo important and interrelated coactors that contribute to excessive rates o perinatal morbidity are chronic hypertension and diabetes, both o which are associated with maternal
obesity. Tese comorbidities each may play a role in the higher
rates o etal-growth restriction and indicated preterm birth that
are seen in obese women (Liu, 2019; anner, 2020). Perinates
o obese women with preterm prematurely ruptured membranes
have a higher incidence o respiratory complications than those
born to normal-weight women (Lynch, 2020). Pregestational
diabetes also raises the birth deect rate, and gestational diabetes
is complicated by excessive numbers o large-or-gestational-age
and macrosomic etuses (Chap. 47, p. 833).
Even when diabetes and hypertension are not considered,
the prevalence o neonatal morbidity is greater in ospring
o obese women (Kim, 2016; Polnaszek, 2018; Schummers,
2015). Te propensity or preterm birth may be related to
increased adipokines and cytokines causing chronic inammation (ersigni, 2020). Te group rom MetroHealth
Medical Center in Cleveland has extensively studied prepregnancy obesity, gestational weight gain, and diabetes
and their relationship to adverse pregnancy outcomes and
to greater newborn weight and at mass (Catalano, 2015;
Ma, 2016; Yang, 2016). Although each o these variables is
associated with larger and more corpulent newborns, prepregnancy BMI and its eect on inammation and placental
gene expression has the strongest inuence on the prevalence
o macrosomic neonates.
Rates o birth deects also are higher with obesity (Auger,
2019). For neural-tube deects, elevated risks o 1.2-, 1.7-,
and 3.1-old have been described or overweight, obese, and
severely obese women, respectively (Rasmussen, 2008). Te
National Birth Deect Prevention Study reported a correlation between BMI and congenital heart deects (Gilboa, 2010).
However, this may be related to diabetes as a coactor (Biggio,
2010). Importantly, obesity degrades the accuracy o obstetrical
ultrasound examination and antepartum identication o birth
deects (Adekola, 2015; Dashe, 2009; Yaqub, 2021).
■ Longterm Offspring Morbidity
Obese women beget obese children, who themselves become
obese adults. Catalano and coworkers (2009) studied ospring
at a mean age o 9 years and ound a direct association with
maternal prepregnancy obesity and childhood obesity. Tey
also reported associations with central obesity, elevated systolic
blood pressure, increased insulin resistance, and lipid abnormalities—all elements o the metabolic syndrome. Reynolds
and associates (2013) reported higher rates o cardiovascular
disease and all-cause mortality in 37,709 adult ospring o
overweight and obese mothers. Similar cardiometabolic health
eects in ospring were echoed by Gaillard and colleagues
(2016). Other data suggest that excessive maternal weight gain
in pregnancy may predict obesity in adult ospring (Lawrence,
2014). Last, rates o glucose intolerance and metabolic syndrome are higher among ospring o obese women (Gaillard,
2016).
Te potential biological mechanisms o these associations
are unclear. But such studies raise the possibility o fetal programming, that is, the etal environment may lead to adverse
adult health outcomes. Elucidation is limited by insufcient
data regarding the inuence o maternal and genetic predisposition compared with the diet and activity environment o the
inant and child (Gluck, 2009). Te science o epigenetics has
provided some support or the possibility that perturbations o
the maternal–etal environment can adversely alter postdelivery
events (Kitsiou-zeli, 2017).
ANTEPARTUM MANAGEMENT
■ Maternal Weigt Gain
Te Institute o Medicine (2009) has updated its previous
maternal weight gain determinants (able 10-4, p. 183). For
overweight women, weight gain o 15 to 25 pounds is suggested. For obese women, the Institute recommends a gain o
11 to 20 pounds. Intuitively, maternal weight must increase
sufciently to provide or etal and placental tissue accrual
and or amnionic uid and maternal blood volume expansion.
Tus, maternal weight loss during pregnancy is discouraged.
Te American College o Obstetricians and Gynecologists
(2021) endorses these guidelines.
It is emphasized that these recommendations were issued
without rm scientic evidence to support them, and their
value remains unproven (Comstock, 2019; Most, 2019). For
example, recent studies dier with respect to the eect o insu-
cient weight gain or obese women. Bodnar and colleagues
(2016) reported no greater risk or low-birthweight or small-
or-gestational-age newborns among 47,494 obese women who
had inadequate weight gain during pregnancy. Bogaerts and
associates (2015) also ound that even weight loss among obese
women did not yield poor etal growth. In contrast, however,
Hannaord and coworkers (2017) reported that obese women
who gained less than the Institute recommendations were
almost three times more likely to deliver a small-or-gestationalage neonate. Another study similarly ound an almost twoold
greater risk o growth-restricted newborns among obese women
who lost weight during pregnancy (Cox Bauer, 2016).
Excessive gestational weight gain may portend greater risks
or the obese mother. Berggren and coworkers (2016) noted that
overweight and obese women accrued maternal at with excessive
gestational weight gain. From another analysis, overall higher
rates o hypertensive disorders, cesarean delivery, and etal overgrowth and lower rates o spontaneous preterm birth and etal
undergrowth were ound among women gaining more than recommended (Johnson, 2013). However, when analyzed according to BMI category, signicantly higher rates o preeclampsia,
cesarean delivery, and etal overgrowth were identied among
the 1937 overweight women, but not the 1445 obese women,
who gained excess weight. Last, overweight and obese women
have excessive postpartum weight retention (Siegel, 2020).
■ Dietary Intervention
Several dietary interventions can help limit and achieve the
weight gain targets listed in the previous section. Options
include liestyle changes such as changes in physical activity. In
one randomized trial o exercise in 300 overweight women, risks
or gestational diabetes were lowered (Wang, 2017). In other
trials, however, dietary intervention had no eect on weight gain
(Okasene-Gaa, 2019; Seneviratne, 2016). Also, a Cochrane
database analysis o 11,444 women suggests that liestyle interventions coner only a modest reduction in maternal weight
gain, and their benets or etal overgrowth, cesarean delivery
rate, and adverse neonatal outcome are not signicant (Muktabhant, 2015). Last, metormin treatment or obese pregnant
women does not improve pregnancy outcomes (Dodd, 2018).
Regarding neonatal outcomes, the poor success o liestyle
interventions during pregnancy has been attributed to their
late introduction. In this regard, it is presumed that early gene
expression within the placenta has already been programmed
(Catalano, 2015).
■ Prenatal Care
Close prenatal monitoring detects most early signs o diabetes or
hypertension. Early gestational diabetes screening did not result
in less morbidity compared with standard screening (Harper,
2020). Obstructive sleep apnea is common in obese women
(Dominquez, 2018). Standard screening tests or etal anomalies
are sufcient, while remembering the sonographic limitations
or etal anomaly detection in this group. Even so, ultrasound
predicts etal weight accurately in these women (O’Brien,
2020). Accurate etal-growth surveillance in obese women usually requires serial sonographic assessment. Dude and coworkers
(2019) reported that ultrasound as a detection tool had high
specicity but poor sensitivity or growth restriction and a low
positive predictive value or macrosomia. Antepartum external
etal heart rate monitoring is likewise more difcult.
INTRAPARTUM MANAGEMENT
Obesity poses increased risk or multiple labor or intrapartum
complications. Tese include postterm pregnancy or labor
abnormalities (Carpenter, 2016; Shenouda, 2020). In one
study o 143,519 women, the odds o spontaneous labor at
term in obese women was approximately hal that o normalweight women (Denison, 2008). In an analysis o more than
5000 parturients, women with a BMI >30 kg/m2 had a longer
duration and slower early progression o rst-stage labor (Norman, 2012). Epidural analgesia apparently does not aect the
length o labor in obese women (Polónia Valente, 2020).
■ Labor Induction
As shown in able 51-2, compared with normal-weight women,
obese women are nearly twice as likely to undergo labor induction
(Denison, 2008). However, obese women are more likely to experience a ailed induction, and this risk rises with increasing obesity
(Kerbage, 2020). Te duration o labor resulting in vaginal delivery lengthens with increasing maternal BMI (Carlhäll, 2020). In a
retrospective analysis o 470 nulliparous women with a BMI >30
kg/m2, those who underwent labor induction at 39 weeks’ gestation had a greater cesarean delivery rate—26 versus 40 percent
compared with a cohort expectantly managed (Wole, 2014). In
a study o 485 women with class III obesity, the overall cesarean
delivery rate ater ailed induction was 49 percent (Paidas eeey,
2020). Te rate was 46 percent or those with a BMI 30–40, 63
percent or a BMI 40–50, and 69 percent or a BMI >60.
Although perhaps not unexpected, these ndings have been
challenged. Lee and associates (2016) reviewed statistics rom
74,725 deliveries in obese women and reported that elective
induction at 37 to 39 weeks’ gestation was actually associated
with a lower cesarean delivery rate. Additionally, in a secondary analysis o one randomized trial, obese nulliparas who were
randomly assigned to Foley catheter cervical ripening plus
misoprostol or labor induction had a reduced labor duration
and lower rate o cesarean delivery compared with those given
solely misoprostol (Seasely, 2021). Tese conicting results
highlight the difculties aced by obstetricians as they contemplate the seemingly competing interests o the etus and the
obese mother.
■ Anestesia Risks
Obese women present anesthesia challenges that include difcult epidural and spinal analgesia placement and complications
rom ailed or difcult intubations. Evaluation o gravidas with
supermorbid obesity by the anesthesiologist is recommended
during prenatal care or upon arrival to the labor unit (American
College o Obstetricians and Gynecologists, 2019b).
Regional analgesia or morbidly obese women is associated
with longer neuraxial procedure times and more ailed placement attempts (Li, 2019). Importantly, however, spinal analgesia
in obese women or cesarean delivery does not appear to have
greater benets than combined spinal-epidural. One study comparing single-shot spinal analgesia and combined spinal-epidural
analgesia ound that both methods could be placed with equal
expediency and efcacy in morbidly obese gravidas (Ross, 2014).
Obese women who undergo neuraxial analgesia that is
complicated by relative hypotension more requently have
neonates with umbilical artery cord blood acidemia, which
probably stems rom delayed delivery. One study o 572
obese women showed that cord blood pH signicantly
dropped and base decit rose with increasing BMI (Edwards,
2013). Te rate o gases with a pH <7.1 doubled rom
3.5 percent or a BMI <25 kg/m2 to 7.1 percent or a BMI
≥40 kg/m2. Anesthetic risks and complications are discussed
in Chapter 25.
■ Cesarean Delivery
As shown in able 51-2, rates o cesarean delivery are signicantly
greater in obese women compared with normal-weight gravidas.
In an analysis o 226,958 women, cesarean delivery rates rose
signicantly or overweight (34 percent), class I (38 percent),
class II (43 percent), and class III (50 percent) obesity (Schummers, 2015). Our experiences at Parkland Hospital are similar
(Fig. 51-8). Moreover, obese women had less composite morbidity when labor was attempted compared with cesarean delivery
(Gibbs Pickens, 2018; Grasch, 2017). More worrisome is that
obese women also have higher rates o emergency cesarean delivery,
and obesity lengthens times or decision-to-incision and or delivery (Girsen, 2014; Pulman, 2015).
1990–1991
Cesarean delivery (percent)
40
Normal
Overweight
Obese
30
20
10
0
1992–2001 2002–2012 2013–2019
FIGURE 51-8 Cesarean delivery rates in more than 300,000
women according to BMI categories over a 30-year period at Parkland Hospital.
Discussed in Chapter 31 (p. 577), the incidence o ailed trial
o labor ater cesarean is higher in obese women (Grasch, 2017;
Wilson, 2020). Women who gain weight between pregnancies
also have signicantly lower rates o vaginal birth ater cesarean.
■ Surgical Concerns
For cesarean delivery, orethought is given to optimal placement
and type o abdominal incision to provide access to the etus and
to eect the best wound closure. We preer a vertical incision in
obese women to provide the most direct access (Fig. 51-9). Others preer a low transverse abdominal incision, with or without
rostral taping o the pendulous abdomen (Karimyar, 2020; Lakhi,
2018). Individual dierences in maternal body habitus preclude
naming any one approach as superior (uran, 2016). Some observational studies have compared wound outcomes associated with
A B
FIGURE 51-9 Abdominal incision for the obese woman. A. Frontal view. The dotted line indicates an appropriate skin incision for
abdominal entry relative to the panniculus. As shown by the uterus
in the background, selection of this periumbilical site permits
access to the lower uterine segment. B. Sagittal view.
vertical and transverse skin incisions, but results are conicting as
to a superior option (Karimyar, 2020; Marrs, 2014; Sutton, 2016).
Te requency o abdominal wound inections is directly
related to BMI. Conner and associates (2014) ound the
risk o wound inection is threeold higher—23 versus 7
percent—in women with supermorbid obesity compared
with nonobese patients. Among women with a BMI >45
kg/m2, reported wound complication rates range rom 14
to 19 percent (Smid, 2015; Stamilio, 2014). Comorbid diabetes apparently raises this risk (Leth, 2011). Other studies
describe wound complication rates ranging rom 2 to >40
percent in obese women (Conner, 2014; Marrs, 2014; Smid,
2015; Tornburg, 2012).
Several interventions may be preventive. Closure o subcutaneous tissue when at least 2 cm deep reduces wound complication rates (ipton, 2011). Steel staples and subcuticular skin
closure produce identical results (Zaki, 2018). Studies have also
examined the use o higher doses o perioperative prophylactic
antibiotics. Pharmacokinetic studies indicate that tissue concentrations o prophylactic antibiotics are lower with increasing BMI (Pevzner, 2011; Young, 2015). One prospective study
showed that a 3-g dose o ceazolin resulted in higher tissue
concentrations compared with a 2-g dose (Swank, 2015). A retrospective analysis o 335 women with a median weight o 310
pounds ound that the higher dose o ceazolin did not result
in ewer surgical site inections (SSIs) (Ahmadzia, 2015). Te
American College o Obstetricians and Gynecologists (2020)
recognizes either 2- or 3-g doses o ceazolin as suitable or
those with weights ≥80 kg. Te Centers or Disease Control
and Prevention recommends a 2-g dose or weights ≥80 kg
and 3-g dose or those ≥120 kg (Berríos-orres, 2017). One
pharmacokinetic analysis in obese women showed sufcient
tissue levels with a 2-g dose or cesarean deliveries lasting 1.5
hours. Authors recommended consideration or redosing in
obese women i surgeries were longer (Grupper, 2016). Last,
some early evidence may support extending oral antibiotic prophylaxis or 48 hours postcesarean in obese women to lower
SSIs (Valent, 2017). Obese women administered preoperative
cephalosporin prophylaxis had a surgical inection rate o 13.4
percent compared with a rate o 6.4 percent or those given a
2-day postoperative course o oral cephalexin and metronidazole
in addition to routine preoperative prophylaxis.
Negative-pressure wound therapy (NPW) also has been
used prophylactically (Mark, 2014). o address this, Hussamy
and colleagues (2019) designed a randomized trial o NPW
versus routine dressing in 441 obese women undergoing cesarean delivery. Such therapy did not signicantly lower the postoperative wound complication rate compared with routine
care—17 versus 19 percent, respectively. A subsequent report
conrmed these ndings (uuli, 2020).
For the obese woman who is delivered vaginally, puerperal
tubal sterilization is sae regardless o BMI (Byrne, 2020). Tese
procedures are described in Chapter 39. Te risks or postpartum venous thromboembolism are increased in obese women.
Tis is despite the act that velocity o lower-extremity blood
ow is increased in obese pregnant women (Dutta, 2020). As
discussed in Chapter 55 (p. 990), thromboprophylaxis is controversial. o lower thromboembolic complications, graduated
compression stockings, hydration, and early mobilization ater
cesarean delivery in obese women are recommended by the
American College o Obstetricians and Gynecologists (2019b).
I there are additional risk actors other than class III obesity, the
Society or Maternal-Fetal Medicine (2020) recommends enoxaparin. We do not routinely use thromboprophylaxis or obesity
alone at Parkland Hospital. Tis practice has recently been con-
rmed by Lu and associates (2021).
BARIATRIC SURGERY
Several surgical procedures are designed to treat morbid obesity
either by diminishing gastric volume (restrictive) or by bypassing gastrointestinal absorption (restrictive malabsorptive). In
nonpregnant patients, these procedures serve to improve or
resolve diabetes, hyperlipidemia, hypertension, and obstructive
sleep apnea and to reduce risks o myocardial inarction and
death (Beamish, 2016).
■ Restrictive Procedures
O options, the approved laparoscopic adjustable silicone gastric banding (LASGB) procedure—LAPBAND—places a band
2 cm below the gastroesophageal junction to create a small
stomach pouch above the ring. Te ring diameter is controlled
by a saline reservoir in the band.
Tese procedures can have positive eects on pregnancy outcomes. One study compared pregnancy outcomes in bariatric
surgery patients whose surgery was done ater the rst pregnancy. Following bariatric surgery, the incidences o hypertension, gestational diabetes, and preterm birth were signicantly
lower in the bariatric surgery patients (Ibiebele, 2020). Te
results rom these and other studies are shown in Table 51-3.
Deation o the band during pregnancy aects maternal
and etal weight gain. Pilone and coworkers (2014) studied 22
pregnancies ater band placement and reported that all women
underwent ull deation o the band in the rst trimester and
gained an average o 14.7 kg during pregnancy. In another
study, 42 women underwent deation o the band, whereas
54 women maintained band ination. A deated band was
associated with higher mean maternal weight gain—15.4 kg
versus 7.6 kg, increased birthweight—3712 versus 3380 g, and
a twoold greater risk o macrosomia compared with an inated
band (Cornthwaite, 2015). Rarely, the band may slip due to
nausea and vomiting, especially with advancing gestation or
ater delivery (Pilone, 2014; Schmitt, 2016; Suee, 2012). One
etus suered a atal cerebral hemorrhage caused by maternal
vitamin K deciency secondary to prolonged vomiting due to
band slippage that created a gastric outlet obstruction (Van
Mieghem, 2008).
■ Restrictive Malabsorptive Procedures
Te laparoscopically perormed Roux-en-Y gastric bypass is the
most commonly used procedure or gastric restriction and selective malabsorption. Pregnancy outcomes are changed remarkably ollowing Roux-en-Y bypass (Adams, 2015). As shown in
able 51-3, rates o hypertension, gestational diabetes, and etal
macrosomia are reduced.
Serious complications with bypass operations are uncommon, however, upper abdominal pain is requent in pregnancy
and may be associated with internal herniation, which is protrusion o the bowel through a window deect in the mesentery. Petersen and associates (2017) described outcomes in
a birth cohort including 139 pregnancies. Upper abdominal
pain complicated 46 percent, and a third o these had internal
herniation. Te preterm birth rate was 14 o 64 among those
with upper abdominal pain versus 1 o 75 in those without
pain. Intussusception and small bowel obstruction can develop
rom internal herniation, and maternal deaths rom herniation
and obstruction are reported (Moore, 2004; Renault, 2012).
Bowel obstruction is notoriously difcult to diagnose during
pregnancy (Vannevel, 2016; Wax, 2013).
■ Pregnancy
Because o its associated health successes, bariatric surgery is
popular, and many women subsequently become pregnant
(Narayanan, 2016). From studies, ertility improves and
obstetrical complication rates decline in women ater bariatric surgery compared with morbidly obese controls (Getahun,
2021; Kominiarek, 2017; Yi, 2015). In one o these studies,
despite surgical treatment, almost hal o 670 women were
still obese at the time o their rst pregnancy ater bypass
(Johansson, 2015). Nevertheless, the requency o large-orgestational-age newborns dropped rom 22 to 8.6 percent and
o small-or-gestational-age neonates rose rom 7.6 to 15.6
percent. In a systematic review, Kwong and colleagues (2018)
conrmed these etal weight trends ater bariatric surgery.
According to Maric and colleagues (2020), etuses are smaller
because o lower maternal glucose levels rather than alterations o the etoplacental circulation. Also, risks or diabetes
and preeclampsia were reduced. Last, evidence suggests that
the risk or congenital anomalies is decreased (Auger, 2019;
Neovius, 2019).
Currently, the American College o Obstetricians and Gynecologists (2019b) recommends that women who have undergone bariatric surgery be assessed or vitamin and nutritional
sufciency. When indicated, vitamins B12 and D, olic acid,
and calcium supplementation are given. Vitamin A deciency
also is possible (Chagas, 2013). Women with a gastric band
should be monitored by their bariatric team during pregnancy
because band adjustments may be necessary. Last, special vigilance or signs o internal herniation with intestinal obstruction
is encouraged (Stuart, 2017; Wax, 2013)
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