Learning Objectives:After participating in this continuing professional development activity, the provider should be better able to:
1. Describe the effects of obesity on pregnancy and fetal/neonatal outcomes.
2. Outline patient counseling on the effects of bariatric surgery on pregnancy and fetal/neonatal outcomes.
3. Explain special considerations when taking care of patients who have had bariatric surgery during the prenatal, intrapartum and postpartum periods.
Overview of Bariatric Surgery
Bariatric surgery is a class of weight-loss surgery that works by altering the anatomy of the gastrointestinal tract. According to the National Institutes of Health, candidates for bariatric surgery are: (1) patients with a body mass index (BMI) of 40 or more, or (2) a BMI of 35 or more with a serious health condition linked to obesity including type 2 diabetes, sleep apnea, or heart disease, or (3) a BMI of 30 or more with type 2 diabetes that is difficult to control with medication and lifestyle changes.1 Different institutions may have different criteria or protocols for which patients are candidates for bariatric surgery. Although most patients who have bariatric surgery are adults, teenagers can also be candidates for weight-loss surgery if they have been evaluated by a multidisciplinary team and meet the criteria.
In the United States, the 3 most commonly performed weight-loss surgeries are a sleeve gastrectomy (SG), Roux-en-Y gastric bypass (GB), and an adjustable gastric band (AGB). Other less common weight-loss surgeries include the biliopancreatic diversion with duodenal switch (BPD/DS), which is no longer commonly performed, and a single anastomosis duodenoileal bypass with sleeve gastrectomy (SADI-S), which is a relatively newer procedure.
An SG is a restrictive type of weight-loss surgery where approximately 80% of the stomach is removed. This aids weight loss through a restrictive process, by altering the size of the stomach and thereby reducing the quantity of food the patient can eat, while also removing the portion of the stomach that produces important metabolic hormones including leptin and ghrelin. This surgery is relatively quick, simple, and highly effective, making it the gold standard for weight-loss surgery. A benefit of this surgery is that it can be performed on certain patients who may be considered "high risk" with medical comorbidities. It can also act as a bridge procedure for other weight-loss surgeries including GB and SADI-S procedures. Disadvantages of this surgery are that it is not reversible, it can cause or worsen gastric reflux, and it has less impact on metabolism compared with other weight-loss surgeries.1,2
The GB procedure, also known as Roux-en-Y GB, is performed by dividing the stomach into 2 portions. The smaller portion is connected directly to the small intestine, thereby "bypassing" a larger portion of the stomach and some of the small intestine. A GB promotes weight loss via both restrictive (smaller size of stomach) and malabsorptive (decreasing amount of intestinal absorption) processes. Advantages to this surgery are that the average weight loss is greater and more rapid than with an SG. However, this surgery is longer and more complicated than an SG, which can lead to higher rates of surgical complications. This surgery is also not reversible.1,2
The AGB is a restrictive surgery where a device is placed around the top of the stomach, causing a physical limitation to the amount of food a patient can eat. The size of the device opening can be adjusted. This surgery has the lowest rate of complications, is reversible, and has the lowest risk of vitamin or mineral deficiencies. Although this procedure is relatively safe, weight loss can be slower and less significant than other weight-loss surgeries. There is risk of the band moving or eroding the stomach and there is a relatively high rate of reoperation.1,2
The BPD/DS is a malabsorptive and restrictive bariatric surgery that is no longer popular due to higher complication rates. SADI-S is the newest weight-loss surgery where an SG is performed, then the duodenum is transected and a loop of small bowel is connected to the stomach. Advantages of this procedure include being a simpler procedure and the fact that it is highly effective for weight loss and treatment of type 2 diabetes. This is also a surgery that someone could have if they had already had a gastric sleeve. Disadvantages are similar to other gastric sleeve or bypass surgeries and the fact that this is a newer operation means that less long-term data exist.1,2
Maternal Effects of Obesity During Pregnancy
Obesity is defined as when a person has a BMI of 30 or greater. It can be further classified to class 1 obesity (BMI of 30 to <35), class 2 obesity (BMI of 35 to <40) and class 3 obesity (BMI of >=40). In 2021, 33% of women in the United States between 18 and 44 years of age were obese. Obesity is considered the most common medical condition of reproductive-aged women and is associated with many negative effects on pregnancy, such as increased risk of hypertensive disorders, diabetes, asthma, sleep apnea, cesarean delivery, infection, and thromboembolic disease.3
There are robust data on the increased risk of preeclampsia with obesity. A recent study demonstrated a 2- to 4-fold increase in rates of preeclampsia in pregnant patients with obesity, even after adjusting for preexisting chronic hypertension.4 The mechanism by which obesity increases the risk of preeclampsia is not totally understood; however, it is thought to be related to oxidative stress, inflammation, and altered vascular function.5
The risks of pregestational and gestational diabetes are directly proportional to BMI. The overall risk for pregnant patients developing gestational diabetes with a BMI of 30 or greater is 2.9-fold higher than that of patients with a BMI less than or equal to 20, although depending on population and BMI, the risk has been cited as high as 20-fold higher.6 The risk of developing diabetes is related to whole body insulin resistance and higher plasma insulin concentrations. Given the association between maternal obesity and diabetes, screening recommendations are different for obese versus nonobese pregnant patients. Screening for undiagnosed pregestational diabetes can be considered at the first antenatal visit for patients with a BMI of 35 or greater.3,6
Intrapartum complications associated with obesity include increased risk of cesarean delivery, failed trial of labor, and infection. A meta-analysis showed that the odds ratios (OR) for cesarean delivery for overweight, obese, and severely obese patients are 1.46, 2.05, and 2.89, respectively, when comparing to nonobese patients.3 After adjusting for many cofounders, data show that obesity is associated with a longer first stage, but not a longer second stage of labor.3 According to the American College of Obstetricians and Gynecologists (ACOG) practice bulletin, it is reasonable to allow a longer first stage of labor in an obese person before declaring arrest of dilation. Obesity is not a contraindication to a trial of labor after cesarean delivery; there are conflicting data regarding the vaginal birth after cesarean success rate. One study demonstrated there was a higher risk of composite morbidity and neonatal injury in patients with class 3 obesity who chose an elective repeat cesarean delivery; however, the absolute risk was low.3 The decision to have a trial of labor after cesarean in patients with obesity should be made using shared decision-making with both the patient and their physician.
Similar to intrapartum complications, postpartum complications related to obesity include infection and thromboembolic disease. Pregnancy is considered to be a prothrombotic state, given the venous stasis and activation of the clotting cascade. Obesity and cesarean delivery both increase the baseline risk of thromboembolic disease in pregnancy.5
Fetal and Neonatal Effects of Obesity
Maternal obesity is associated with increased risk of congenital anomalies, most commonly neural tube, cardiac, and facial clefting defects, as described in a systematic review involving 11 countries.7 The ORs were reported to be: neural tube defects [OR, 1.87; 95% confidence interval (CI), 1.62-2.15], spina bifida (OR, 2.24; 95% CI, 1.86-2.69), cardiovascular anomalies (OR, 1.30; 95% CI, 1.12-1.51), septal anomalies (OR, 1.20; 95% CI, 1.09-1.31), cleft palate (OR, 1.23; 95% CI, 1.03-1.47), cleft lip and palate (OR, 1.20; 95% CI, 1.03-1.40), anorectal atresia (OR, 1.48; 95% CI, 1.12-1.97), hydrocephaly (OR, 1.68; 95% CI, 1.19-2.36), and limb reduction anomalies (OR, 1.34; 95% CI, 1.03-1.73). One review suggested nutritional deficiency such as folic acid deficiency as a contributing factor for the congenital anomalies. In addition, increased maternal body mass may impair visualization of fetal anatomy via ultrasound and hence prenatal diagnosis of congenital anomalies, resulting in more undiagnosed neonatal anomalies found at birth. Maternal obesity seems to be associated with lower risk of low birth weight and higher risk of fetal macrosomia and large-for-gestational age infants.7
Maternal obesity is associated with increased risk of spontaneous abortion, recurrent miscarriage, and stillbirth. A meta-analysis published in 2011 demonstrated that people with obesity were 1.3 times more likely to have a miscarriage.8 This association has been confirmed in most other studies of obesity and early pregnancy loss. According to the ACOG practice bulletin on obesity and pregnancy, there is a 3.5 times higher risk of recurrent miscarriage in people with obesity.3 Although the absolute risk of stillbirth is very low, there is a dependent relationship with BMI and stillbirth. A systematic review reported an OR of 1.31 for the association between a maternal BMI of 30 or greater and miscarriages.7 The relative risk of stillbirth in people with obesity ranged from 1.46 to 2.19. In an analysis that looked at BMI class and the relationship to stillbirth by gestational age, people with a BMI of 50 or greater had a 5.7-fold and 13.6-fold greater risk of stillbirth at 39 and 41 weeks, respectively, compared with normal-weight pregnant people.9
Increasing BMI is also associated with increased preterm births, though this is not demonstrated as consistently across reviews.7 There is also associated worse composite neonatal morbidity, including a higher rate of meconium-stained amniotic fluid, lower Apgar scores and arterial cord blood gasses, and more frequent need for neonatal intensive care.7,10 Many studies have also demonstrated an association between prepregnancy and pregnancy obesity and childhood obesity in the offspring: for people who are overweight or obese before pregnancy, there is a 2 to 3 times higher risk of overweight or obesity in the offspring.11
Effects of Obesity and Bariatric Surgery on Fertility
Obesity can negatively impact fertility by increasing the risk of anovulation and altering the menstrual cycle. Increasing BMI is directly proportional to a longer follicular phase and a shorter luteal phase. These changes lead to decreased luteinizing hormone and follicle-stimulating hormone release, which in turn leads to corpus luteum dysfunction. A dysfunctional corpus luteum inhibits the capacity for implantation and maintenance of pregnancy.12 The secretion of leptin, an adipokine hormone, is directly related to total body adiposity and increasing leptin levels are associated with inhibition of ovarian steroidogenesis and follicular growth.12
Bariatric surgery leads to a reduction in obesity, hence has a positive effect on fertility. Bariatric surgery promotes weight loss and decreases total body adiposity. This decrease in adiposity can decrease leptin levels and in turn lead to less interference with the reproductive endocrine system. A study in 2006 demonstrated that 70 of 98 people who underwent bariatric surgery had return of ovulatory function after surgery.12 Another recent study of 20 people with polycystic ovarian syndrome undergoing bariatric surgery reported that 82% of patients experienced normalization of their menstrual cycles after surgery. Of the patients in this study who were unable to conceive before surgery, all who desired to conceive were able to conceive within 3 years.12 However, it is important to acknowledge that bariatric surgery is currently not considered a treatment for infertility.
Effects of Bariatric Surgery on Pregnancy Outcomes
Although the effects of obesity on pregnancy are well-known, there is less data regarding pregnancy outcomes in people who have had bariatric surgery. A retrospective cohort study using the Health Care Costs and Utilization Project-Nationwide Inpatient Sample database (HCUP-NIS) containing data from approximately 20% hospitals across 47 states in the United States compared pregnancy outcomes between patients with prior bariatric surgery and morbidly obese patients. Patients with prior bariatric surgery had lower rates of hypertensive disorders, premature rupture of membrane, chorioamnionitis, cesarean delivery, instrumental delivery, postpartum hemorrhage, and postpartum infection. However, they had higher rates of induction of labor, postpartum blood transfusions, venous thromboembolisms, and fetal growth restriction. There were no differences observed in rates of preterm births, stillbirth, or reported congenital anomalies.13
A nationwide cohort study out of Sweden that compared pregnancy outcomes in people who had bariatric surgery with people with similar characteristics but without bariatric surgery demonstrated an increased risk of preterm birth and small-for-gestational age infants in patients who had bariatric surgery and a resulting BMI of less than 35, compared with their matched counterparts with similar characteristics. People with bariatric surgery had a lower incidence of large-for-gestational age infants. There was also a lower risk of gestational diabetes in patients who had bariatric surgery.14
A systematic review was performed looking at studies published from years 2000 to 2015 that examined the health effects of pregnancy after bariatric surgery. Thirteen studies were included and demonstrated that, compared with BMI-matched controls without surgery, bariatric surgery before pregnancy reduced infant birth weight. There was no effect on total maternal gestational weight gain or Apgar scores. There was no increased risk of adverse neonatal birth outcomes, and the effect on maternal complications and cesarean delivery rates was inconsistent.15 As bariatric surgery continues to increase in popularity, there is room for further investigation into the effect on pregnancy outcomes.
Antenatal Considerations for Patients Who Have Had Bariatric Surgery
Nutritional Deficiencies
Patients who have had bariatric surgery are at risk for nutritional deficiencies before and during pregnancy, more common after malabsorptive procedures as compared with restrictive bariatric procedures. Nutrients commonly found to be deficient in postbariatric surgical patients include protein, iron, vitamin B12, folate, vitamin D, and calcium.16 Monitoring of levels of those nutrients should be considered every trimester for pregnant patients. Of those nutrients, special consideration should be given to iron and folate as pregnancy is a predisposition to iron-deficiency anemia and folate is important for prevention of fetal neural tube defects. Although some sources suggest increased intake of folic acid supplementation for postbariatric surgery patients, there is currently no consensus for recommendation of higher than standard dosages for iron (27 mg daily) and folate (400 [mu]g daily) supplementations for postbariatric surgery patients without other indications. If deficiencies are present, oral supplementations can be considered initially; parenteral supplementations can be considered if there is inadequate response to oral replacement. Nausea and vomiting are common in pregnancy and can be exacerbated by postbariatric surgery status due to decreased stomach volume. In patients with significant nausea and vomiting, vitamin B1 deficiency and supplementation should be considered. Common therapies for nausea and vomiting during pregnancy might also have limited effectiveness due to varied absorption of medications. Therefore, nonoral therapies, such as oral dissolving formulations or suppositories, can be considered.
Pregnant patients who have had bariatric surgery should be encouraged to have adequate intake of at least 60 g of protein per day.17 Protein deficiency can be associated with poor fetal growth and poor wound healing, which can be significant for healing from cesarean delivery in the postpartum period.
Maternal Weight Monitoring
Maternal weight should be closely monitored during the prenatal period after bariatric surgery. Weight loss should be avoided during pregnancy as it can be associated with poor fetal growth. Care also needs to be taken to avoid excessive maternal weight gain, as excessive weight gain in pregnancy is associated with adverse pregnancy outcomes such as fetal macrosomia.17 Currently, there is no guideline on gestational weight gain specific to postbariatric surgery patients. In addition, pregnancy does not appear to affect long-term weight-loss effectiveness of bariatric surgery, and pregnant patients should follow normal recommendations for gestational weight gain regardless of bariatric surgery status.18
Antenatal Testing
Screening for gestational diabetes is normally done using an oral 50-g glucose solution administration followed by checking blood glucose level 1 hour afterward. This regimen may not be well-tolerated by patients who have undergone bariatric surgeries due to the volume intake over a short period and the risk of dumping syndrome in these patients. Dumping syndrome occurs after a rapid emptying of hyperosmolar gastric contents into the intestinal tract, causing symptoms such as abdominal pain, nausea, vomiting, diarrhea, dizziness, flushing and, palpitations, most commonly within 60 minutes of ingestion but can be up to 3 hours after ingestion. In addition, due to malabsorption, there may be a concern regarding accuracy of the test results. Although there is no consensus on gestational diabetes screening in postbariatric surgery patients, alternatives to the conventional screening method can be considered. One of the most widely used alternatives is checking capillary glucose values fasting and 2-hour postprandial for 1 week between 24 and 28 weeks of gestation (when screening for gestational diabetes normally occurs).17 This method is also used in patients who did not have bariatric surgeries but otherwise cannot tolerate the 50-g oral solution.
Because postbariatric surgery patients are at risk for nutritional deficiencies and inadequate weight gain during pregnancy, fetal growth monitoring with ultrasound can be considered in the third trimester.
Bariatric Surgery-Related Complications
Two common complications related to bariatric surgery were found in pregnancy: internal herniation after Roux-en-Y GB and gastric band slippage after AGB.17 Those complications can present with symptoms similar to pregnancy-related symptoms, such as epigastric pain, nausea, and vomiting, causing delay in diagnosis. Internal herniation can lead to bowel obstruction and, without timely intervention, can have catastrophic consequences. As such, care providers should have a high index of suspicion when pregnant patients with prior bariatric surgery present with these symptoms, especially if they persist despite conventional therapy.
Intrapartum Considerations for Patients Who Have Had Bariatric Surgery
Bariatric surgery alone is not an indication for delivery at a certain gestational age or cesarean delivery. Patients who have had prior bariatric surgery should undergo similar labor and delivery management as those who have not. A retrospective cohort study of more than 3.6 million deliveries in the United States in 2012, of which 0.2% of the patients had a history of bariatric surgery, reported significantly higher rates of anesthesia complications (0.7% vs 0.3%) and puerperal infections (1.9% vs 0.8%) in patients with a history of bariatric surgery than patients without prior bariatric surgery.19
Postpartum Considerations for Patients Who Have Had Bariatric Surgery
Pain Management
The malabsorptive and/or restrictive characteristics of postbariatric surgery patients should be taken into consideration when managing pain in the postpartum period. Extended-release pain medication preparations should be avoided. Instead, immediate-release, oral solution or suppository formulations should be considered. In addition, caution should be used when using oral nonsteroidal anti-inflammatory drugs (NSAIDs) due to risk of gastric ulceration.20 For patients who have cesarean deliveries, a multimodal pain management approach should be considered, such as a transversus abdominis plane (TAP) block, to provide adequate postoperative pain control while minimizing the need for and risk of dependence on narcotic-containing medications.
Breastfeeding
A systematic review of 11 observational studies on the effect of bariatric surgery on breastfeeding suggests that breast milk after bariatric surgery is adequate in nutrients provided that the breastfeeding person has good nutritional status. In case studies where nutritional deficiencies were reported in the infants, there was no long-term effect reported after deficiencies were corrected.21
Psychological Wellness
Some studies have demonstrated increased risk of being diagnosed with a psychiatric disorder in people evaluated for bariatric surgeries, with a 22% to 32% reported prevalence for mood disorders such as depression or anxiety.22 Having preexisting psychiatric disorders is known to be associated with increased risk of peripartum mood disorders, particularly depression. An observational study including 91 postbariatric surgery patients demonstrated a significantly higher rate of postpartum depression in those patients compared with obese controls (38% vs 18%, P < 0.0001).23 Another study including 1427 bariatric surgery patients reported a 1.51 higher odds of depression and/or anxiety during pregnancy compared with nonsurgical patients with obesity.24
Reproductive Health Services for Patients Who Have Had Bariatric Surgery
People who have had bariatric surgery may need other reproductive health services such as contraception and/or abortion. Due to the malabsorptive nature of certain types of bariatric surgeries, oral contraceptive options, including combined estrogen-progesterone pills or progesterone-only pills, may provide suboptimal contraceptive effectiveness, as the bioavailability of those medications is dependent on the gastrointestinal pH and the amounts of gastrointestinal transporters. However, limited data are available on the effectiveness of oral contraceptives after bariatric surgery. A systematic review of 5 observational and pharmacokinetic studies demonstrated no significant decrease in effectiveness of oral contraceptives in bariatric surgery patients.25 It is suggested that patients who had bariatric surgery use alternative nonoral forms of contraceptives.
Similarly, after malabsorptive bariatric surgery there may be potential for decreased effectiveness of oral medications used for emergency contraception such as ulipristal acetate or levonorgestrel, or medications used for termination of pregnancy such as mifepristone and misoprostol. Patients should receive proper counseling of the potential of decreased effectiveness. However, this should not present as a barrier to access to necessary medical services for people seeking emergency contraception or termination of pregnancy. When possible, alternative routes of administration should be considered, such as buccal or vaginal routes for misoprostol, or a copper-containing intrauterine device as emergency contraception.
Conclusion
Bariatric surgery decreases the prevalence of obesity, and hence has the potential to mitigate the risks of many negative effects associated with obesity during pregnancy. However, obstetrical and reproductive health care providers need to be mindful of special considerations when caring for patients who have undergone bariatric surgery during the preconception and prenatal, intrapartum, and postpartum periods to optimize health outcomes for these patients.
Practice Pearls
* The 3 most commonly performed bariatric procedures in the United States are gastric sleeve, Roux-en-Y GB, and AGB. They cause weight loss through a restrictive or malabsorptive process or a combination of both.
* Obesity is defined as having a BMI of 30 or greater.
* Obesity has been shown to be associated with increased morbidity during pregnancy including increased risks of hypertensive disorders, diabetes, asthma, sleep apnea, cesarean delivery, infection, and thromboembolic disease.
* Maternal obesity is associated with increased risk of pregnancy loss, congenital anomalies, fetal macrosomia, large-for-gestational age infants, preterm birth, stillbirth, and childhood obesity.
* Bariatric surgery seems to have a positive impact on fertility, though it is not recommended as a treatment for infertility.
* Bariatric surgery seems to be associated with lower risks of hypertensive disorders, premature rupture of membrane, chorioamnionitis, cesarean delivery, instrumental delivery, postpartum hemorrhage, and postpartum infection.
* Bariatric surgery seems to be associated with higher rates of induction of labor, postpartum blood transfusions, venous thromboembolisms, and fetal growth restriction.
* Patients who have had bariatric surgery are at risk for nutritional deficiencies during pregnancy. It is reasonable to assess protein, iron, vitamin B12, folate, vitamin D, and calcium levels every trimester and supplement as indicated.
* There is no specific guidance for gestational weight gain in postbariatric surgical patients. They should follow the normal recommendation for gestational weight gain.
* Screening for gestational diabetes in postbariatric surgical patients might not be feasible using the conventional 50-g glucose tolerance test due to risk of dumping syndrome. Alternative methods such as postprandial glucose monitoring can be considered.
* Fetal growth ultrasound and antenatal testing can be considered due to risks of nutritional deficiencies and inadequate weight gain during pregnancy in postbariatric surgical patients.
* Complications of bariatric surgery can present with overlapping symptoms of pregnancy such as nausea, vomiting, and epigastric pain; therefore, providers should have a high index of suspicion when caring for these patients.
* Patients who have had prior bariatric surgery should undergo similar labor and delivery management as other patients. Bariatric surgery is not an indication for cesarean delivery.
* Bariatric surgery status should be taken into consideration when managing pain in the postpartum period due to concern for gastric ulceration associated with NSAID use.
* Patients who had prior bariatric surgery are at high risks of peripartum depression and anxiety.
* Due to the malabsorptive nature of some bariatric surgeries, consideration needs to be taken when oral formulation of medications is administered including medications for reproductive purposes such as abortion or contraception.
References