SL is a 29-year-old woman with a height of 5'3" and weight of 275 lb, who visits her primary medical doctor for an annual exam. She mentions that she is trying to conceive. Her doctor calculates her body mass index (BMI) at 48 kg/m2, putting her into the severely obese (class 3) category. She is otherwise healthy. Her doctor advises weight loss and suggests she consider bariatric surgery, prior to conception, in order to reduce her risk of pregnancy complications.
Women's health pro viders are increasingly managing severe obesity and its associated pregnancy complications in their practices. Th is article discusses the diagnosis of obesity, implications of obesity on maternal and fetal health, preconception, prenatal and delivery considerations for obese women, and management of pregnancy following bariatric surgery.
How do you diagnose obesity, and what is the scope of the problem among pregnant women? BMI is a common and simple method for diagnosing obesity, calculated as weight in kilograms divided by height in meters squared. (For a useful online BMI calculator, see www.nhlbisupport.com/ bmi.) Severity of obesity is defi ned as class 1 (BMI, 30-<35), class 2 (BMI 35-<40), and class 3 (BMI ≥40).1 During 2007 and 2008, 34% of all reproductive-age women in the United States were obese (BMI ≥30), 19% had class 2 obesity, and 8% had class 3 obesity. In addition, since 1980 the distribution of BMI in the population has shifted to the right, indicating that overall, people are becoming heavier and meeting the criteria for the highest BMI categories.1
back to top
What are the perinatal risks associated with obesity? Obesity is a risk factor for pregnancy complications including gestational diabetes mellitus, hypertension in pregnancy, fetal macrosomia, and congenital anomalies.2 Risk for cesarean delivery increases with BMI and is almost 3 times higher for women with class 2 obesity compared with women with a normal BMI. Higher BMI is associated with increased risk for wound infection and breakdown.2 In addition, obesity in pregnancy is associated with increased utilization of health care services.3
What are preconception care considerations for severely obese women?Preconception counseling is aimed at achieving a healthier weight prior to conception, with a goal of normalizing BMI. Because obese women are at increased risk for complications, all primary care visits with women of reproductive age present an opportunity to optimize preconception health (Table 1). ACOG recommends counseling all overweight and obese women about potential pregnancy complications, including fetal risks.2 Clinicians should also screen for medical complications, such as type 2 diabetes or hypertension. Preconception visits provide a chance to recommend weight loss, including referral to a nutritionist, structured weight management program, or a bariatric surgeon. Finally, obese women who are not yet medically optimized should receive reliable contraception.
Does weight loss prior to pregnancy reduce complications? Weight loss studies in the general population show that adherence to strict diets and exercise can help people decrease weight, but maintaining weight loss over time is diffi cult.4 To our knowledge, no trials have addressed prepregnancy weight loss interventions and pregnancy outcomes for obese women.
Bariatric surgery is an eff ective therapy for obesity, resulting in signifi cant weight loss and improvement in many comorbidities.5 Women accounted for 83% of all bariatric surgery procedures in the 18 to 45 age-group between 1998 and 2005.6 While there is evidence that bariatric surgery reduces the risk of perinatal complications, most studies have been small, short-term, and without detailed information about fetal outcomes.6 To be a surgical candidate, insurance companies require either class 3 obesity, or class 2 obesity with associated comorbid conditions, such as type 2 diabetes.
back to top
What are prenatal care considerations for severely obese women?When fi rst presenting for prenatal care, obese women should receive counseling about the potential maternal and fetal risks, as well as expectations for gestational weight gain to reduce these risks. Studies consistently show a relationship between gestational weight gain and neonatal birth weight, including risk for macrosomia. Higher weight gain is also associated with risk for cesarean delivery, but the relationship is confounded by prepregnancy weight.
The Institute of Medicine recently revised its 1990 guidelines, as reported in "Weight Gain During Pregnancy: Reexamining the Guidelines" (Table 2).7 For women with a prepregnancy BMI of ≥30, the recommended range of weight gain is 5 to 9 kg (11- 20 lb). However, there are no recommendations specifi cally for women with class 3 obesity, and few studies have prospectively assessed outcomes of limiting weight gain. A few small studies have examined interventions to help women gain pregnancy weight within recommended guidelines, but they have not shown any impact on birth weight, preeclampsia, or pregnancyinduced hypertension.7
Although the benefits of an earlier diagnosis of gestational diabetes have not been well established, ACOG suggests screening obese women for the condition earlier in pregnancy. A positive test likely indicates prepregnancy type 2 diabetes that had not yet been diagnosed. If the test is negative, however, women should undergo the glucose challenge test at the standard time between 25 and 28 weeks.2
Indications for cesarean delivery are the same for obese and nonobese women. Since obese women are at risk for anesthetic complications such as difficulty obtaining neuraxial anesthesia, as well as failed or difficult intubations, an anesthesia consultation could be considered prenatally or early during intrapartum management.2
back to top
What are specifi c considerations for managing pregnancy after bariatric surgery? Most surgeons recommend waiting 12 to 18 months after surgery before conception, to avoid pregnancy during the period of rapid weight loss. A recent retrospective cohort study by Sheiner et al compared 104 women who conceived within one year of surgery with 385 who conceived after one year and showed no diff erences in birth weight, anemia, preterm delivery, and other short-term perinatal outcomes.8
The most common bariatric surgical procedure in the United States is Roux-en-Y gastric bypass, which has both malabsorptive and restrictive effects and may result in nutritional defi ciencies. The study by Sheiner et al included only 4 patients who conceived within one of year surgery and had undergone gastric bypass surgery, limiting its generalizability. Because of the risk for nutritional defi ciencies, prior to or early in pregnancy women should be screened and treated for vitamin deficiencies, including iron, vitamin D, vitamin B12, folate, and calcium.9
Although post–bariatric surgery pregnancy is generally considered safe, rare complications including hernias, small bowel ischemia, vomiting, gastrointestinal bleeding, anemia, and intrauterine growth restriction have been reported. In addition, following adjustable gastric banding, some patients may require removal of fl uid from the band to relieve gastrointestinal symptoms during pregnancy and facilitate appropriate weight gain.9
Dumping syndrome can occur after a malabsorptive gastric bypass procedure; therefore, the standard glucose challenge test should be avoided. Alternatively, the patient can monitor her fasting and postprandial blood sugar for a week between 25 and 28 weeks to screen for gestational diabetes.10 Cesarean delivery rates are high after bariatric surgery, even after controlling for obesity, but a history of bariatric surgery should not alter the labor and delivery course.2
back to top
What are considerations for postpartum care for severely obese women? ACOG recommends screening all women who had gestational diabetes for type 2 diabetes at 6 to 12 weeks postpartum. A fasting plasma glucose or a 75-g oral glucose tolerance test can be used for screening.11 In the postpartum period, weight loss is particularly important, as postpartum weight retention can signifi cantly increase future risk for obesityrelated chronic diseases. In addition to its benefits for the baby, breastfeeding may promote postpartum weight loss for women in all prepregnancy BMI categories.12
Clinicians may also consider referring a severely obese patient for subsequent follow- up with an internist to promote weight loss eff orts and medical management to achieve a healthier weight in the interconception period, as well as to prevent longerterm obesity-associated complications like heart disease and diabetes.
Women's health clinicians need the tools to diagnose and optimize the reproductive health of obese women prior to conception, during pregnancy, and postpartum, as obesity increases in the United States. Early diagnosis and management of gestational diabetes may improve neonatal health outcomes. Although bariatric surgery for women who meet criteria may prevent perinatal complications, women who have bariatric surgery require special care during pregnancy with a targeted assessment of vitamin defi ciencies and appropriate replacement. Th roughout their reproductive life course, obese women will need tailored counseling about the risks of obesity, benefi ts of weight reduction and limited gestational weight gain, and eff ective interventions to improve long-term maternal health, as well as fetal outcomes.
The authors report no actual or potential conflicts of interest in relation to this article.
back to top