That Bump’s a Baby Now: Pregnancy After Weight Loss Surgery
By Kathryn M. Lito, MPH, RD, LD
Vol. 10 No. 12 P. 48
Conceiving after surgery is certainly feasible, but experts stress the importance of first helping hopeful mothers-to-be stabilize their weight and resolve critical nutrient deficiencies.
The increasing prevalence of obesity in the United States is affecting Americans regardless of age, gender, or ethnicity. From 2003 to 2004, more than 66% of adults aged 20 and older were overweight (a body mass index [BMI] greater than or equal to 25). The prevalence of obesity (a BMI greater than or equal to 30) was 32%, and morbid obesity (a BMI greater than or equal to 40) was nearly 5%.1 Concurrently, the number of weight loss surgeries each year continues to rise, with more than 175,000 procedures in 2007 and 205,000 in 2008, according to American Society for Metabolic and Bariatric Surgery estimates.
Since more than 70% of patients undergoing any form of bariatric surgery are female, many of whom are of reproductive age, it is no surprise that obstetricians are seeing an increasing number of women who have had weight loss surgery.2 While weight loss surgery aids patients in achieving significant weight loss, many women who present to their obstetrician postsurgery may still be obese, especially if their pregnancy was unplanned. According to the March of Dimes, there are many adverse outcomes associated with maternal overweight and obesity, including hypertension, gestational diabetes mellitus, preeclampsia, neural tube and other birth defects, delivery of large-for-gestational-age infants, labor and delivery complications, and fetal and neonatal death. Depending on the type of surgery and length of time post-op, nutritional risks may also be a reality.
Subsequently, healthcare professionals must understand the inherent risks and complications and the appropriate treatment and care related to pregnancy after bariatric surgery.
Those who have worked with female patients who are obese know that infertility and disruptions in reproductive health are common comorbidities. While a certain amount of body fat is essential to the reproductive system, greater-than-normal amounts can lead to hormonal imbalances. Large amounts of adipose tissue, characteristic of women with morbid obesity, result in increased estrogen production and storage in fat cells outside the ovaries. Overproduction of exogenous estrogen and other sex hormones is not well regulated, increasing the likelihood of anovulation, dysfunctional uterine bleeding, and decreased fertility.
As BMI decreases (as is the case after weight loss surgery), circulating hormones decrease, resulting in more efficient hormonal feedback mechanisms. This helps women reduce the frequency of menstrual irregularities, achieve a more consistent ovulatory pattern, and, ultimately, improve fertility and the likelihood of pregnancy.3 It is not uncommon for women presenting for bariatric surgery to believe they cannot get pregnant because they have tirelessly tried for years without success. As a result, they may not habitually use contraception, which can lead to postoperative pregnancy as fertility improves.
In addition to improved hormonal balance, other factors affect the probability of pregnancy, including the following:
• Many surgeons instruct patients to discontinue oral contraceptive use prior to surgery to help prevent deep vein thrombosis, breaking the regimen.
• Afterwards, the patient’s oral medication regimen may suffer disruptions for varying lengths of time. Since weight loss occurs rather rapidly, regulation of reproductive hormones and fertility can improve quickly; if patients do not promptly reinstitute a reliable form of contraception, they may unknowingly conceive.
• Prophylactic antibiotics taken postoperatively may interact with and compromise the effectiveness of oral contraceptives.
• Following gastric bypass surgery, the body’s absorption of food and medications varies due to intestinal rerouting; therefore, the oral contraceptive pill is considered unreliable since it is metabolized through the digestive system.
• The patient’s sexual activity may increase as her weight decreases.
Taking these factors into consideration, professionals should strongly encourage women who are capable of conceiving to use multiple forms of birth control to avoid pregnancy until their weight stabilizes. Many bariatric surgery programs encourage women to wait at least 12 to 18 months after surgery to conceive.
Preconception and Antepartum Concerns
Once their weight has stabilized, typically within one to two years postsurgery, women desiring to become pregnant should schedule a preconception consultation with their primary care physician and/or obstetrician, who should then review their medical record and current medications and perform pertinent laboratory analysis. Women should also contact their bariatric surgeon to discuss their specific plan of care. Oftentimes, a bariatric surgeon will know to order baseline labs and refer the patient to a dietitian for a nutritional assessment to evaluate nutritional status and detect and correct nutrient deficiencies.
Many factors affect patient status, including type of weight loss surgery and length of time since surgery. Procedures are divided into three types: restrictive (ie, adjustable gastric band), malabsorptive (ie, biliopancreatic diversion with duodenal switch), and combination (ie, Roux-en-Y gastric bypass). This article will discuss adjustable gastric band and Roux-en-Y gastric bypass.
Regardless of type, all weight loss surgeries restrict food intake. Whether or not a woman is aware she is pregnant, she may be challenged to meet nutritional needs for herself and her developing fetus with such a limited intake. Due to the adjustable gastric band’s adjustability, saline can be removed from the band to minimize restriction and allow optimal nutrition at any time. Nonadjustable, malabsorptive procedures present a challenge, as a higher risk of nutrient deficiencies inherently accompanies them. The Roux-en-Y gastric bypass, one of the most common weight loss surgeries, bypasses the majority of the stomach, duodenum, and proximal jejunum, thereby intentionally causing nutrient malabsorption. The most commonly seen micronutrient deficiencies include iron, vitamin B12, calcium, and vitamin D. While thiamine and folic acid deficiencies are not seen as frequently, they also occur and are just as important to monitor.4
Depending on the length of time since their surgery, women may experience rapid weight loss with or without coexisting surgically stimulated problems, including nausea, vomiting, food intolerance, and dumping syndrome. Professionals must recognize methods for managing these issues.
One area of concern among this patient population is optimal weight gain during pregnancy. Balance is the goal—gaining enough weight for normal fetal growth and development while avoiding gaining too much to minimize obstetric risk, macrosomia, and postpregnancy weight retention. The Institute of Medicine’s recommendations for weight gain during pregnancy are used as a guide (see Table 1).
Postsurgery BMI should be used to determine desirable weight gain. For some, weight gain may be extremely difficult. It is important that these patients have regular ultrasounds to monitor fetal growth. For patients with an adjustable gastric band who experience nausea and/or vomiting during pregnancy, deflating the band may help alleviate symptoms. But if the band is not readjusted at a later time, patients may gain an excessive amount of weight due to lack of restriction. For example, in a 2001 study, all fluid was removed from patients’ bands as early as possible during pregnancy.5 Fluid was added after 14 weeks gestation in most patients. Those who had no fluid added and did not participate in planned active management gained excessive weight. Careful monitoring throughout pregnancy is important to help patients gain a healthy amount of weight.
Dumping syndrome is a postoperative concern for patients who have had gastric bypass. This phenomenon occurs following ingestion of osmotically active solids and liquids (ie, sugar) when gastric pouch contents are rapidly emptied into the small intestine. A variety of uncomfortable symptoms may arise, including diarrhea, nausea, abdominal cramps, bloating, perspiration, shakiness, heart palpitations, and faintness.6 This may present a problem when screening for gestational diabetes mellitus with the oral glucose tolerance test around 28 weeks gestation. As expected, the administration of a 50-gram or larger bolus of glucose may trigger the aforementioned symptoms. If a patient is likely to experience dumping syndrome, alternatives include measuring fasting blood glucose periodically and/or conducting two-hour postprandial readings for at least one week to assess for blood glucose variances.7 Women who conceive after a longer postsurgical period may be able to handle the oral glucose tolerance test.
Another consideration is the risk of complications during pregnancy related to the surgery. Postoperatively, patients who have had Roux-en-Y gastric bypass may be at risk for serious complications such as internal hernias and small bowel obstructions.8 Patients who are pregnant may be at an increased risk for hernias due to increased intra-abdominal pressure and the uterine changes that occur during pregnancy. According to Bellanger and colleagues, “Obstruction, incarceration, and strangulation of bowel from an internal hernia can occur in the pregnant patient, leading to significant morbidity and mortality for the patient and/or unborn fetus.”9 Note that in these cases, as well as other case reports in the literature, many patients’ presentation were subtle and easily confused with common pregnancy-related complaints such as morning sickness, hyperemesis, gastroesophageal reflux, and Braxton-Hicks contractions.
While patients with the adjustable gastric band can experience complications such as band leakage, band migration, and gastric prolapse, the adjustability and reversibility of this procedure decrease adverse outcomes to mother and fetus.
Professionals working with patients who have had bariatric surgery need to be aware of these possible complications and explore all causes via routine tests, CT scans, and even surgical exploration because delaying diagnosis of a serious complication may be detrimental or even fatal.
Either before a woman conceives or once her pregnancy is affirmed, a nutrition professional should perform a complete nutritional workup. As previously mentioned, blood work evaluating pertinent micronutrients (eg, iron, vitamin B12, folic acid, vitamin D, thiamin) may be helpful for detecting deficiencies. Remember to interpret laboratory findings using pregnancy values since there can be fluctuations due to metabolic and volume changes associated with pregnancy. Ask the patient about complaints regarding nausea, vomiting, and food intolerance and evaluate for potential disordered eating such as binge eating, pica, and food aversions.10 To help ease nausea, encourage patients to eat several small meals throughout the day with a blend of protein and complex carbohydrates and to separate solid meals from liquids.
In addition to performing a 24-hour dietary recall or food frequency questionnaire, ask the patient about her supplementation regimen and compliance. Women capable of conceiving must have adequate folic acid prior to pregnancy to minimize the risk of neural tube defects. Research shows that women who are obese are at a significantly greater risk for neural tube defects compared with women with normal BMI.11 Weight loss itself requires higher concentrations of folate (and vitamin B12) to maintain normal homocysteine levels.12 The presence of hyperhomocysteinemia is dangerous in pregnancy as it’s shown to be an independent risk factor for vascular disease of the placenta. A compromised placenta impairs nutrient transfer to the fetus and may result in early pregnancy loss.13 To prevent hyperhomocysteinemia, a prenatal vitamin with adequate folic acid (0.8 to 1 milligram) should be taken daily. While patients who have had Roux-en-Y gastric bypass should take a vitamin B12 supplement postoperatively, patients with the adjustable gastric band may also need a supplement if there is a deficiency.
Advise patients to avoid taking multiple prenatal vitamins to prevent ingesting excessive nutrients; specifically, vitamin A doses greater than 5,000 international units per day may be teratogenic. While we do not want to scare patients into taking appropriate supplements, we should educate them about the importance of supplementation and provide thorough instruction. It is generally recommended to increase total caloric intake by 300 kilocalories per day during the second and third trimesters. This may be a challenge for some women if pregnancy occurs early after surgery; therefore, individualized diet plans are essential. Aim for 71 grams of protein per day, the dietary recommended intake for women who are pregnant. Since this is based on normal-weight pregnant women, readjust needs for your patient as necessary (ie, 1.1 to 1.5 grams of protein per kilogram of ideal body weight). A liquid protein supplement can be used in addition to oral intake to help meet daily caloric and protein needs.14
Is Pregnancy Safe After Surgery?
Taking all of this information into account, it is interesting to note that most studies indicate safe and relatively uncomplicated pregnancies for postoperative bariatric patients, with outcomes similar to patients who have not had weight loss surgery. This is seen in both Roux-en-Y gastric bypass and adjustable gastric band studies.5,15-20 Ideally, a patient should plan for enough time between surgery and pregnancy to allow weight to stabilize and correct any nutrient deficiencies. Since this is often not the case, the provision of a strong team of experts is imperative for monitoring progress throughout the pregnancy.
There Is No “I” in Team
Following bariatric surgery, women who are pregnant need the care of a knowledgeable multidisciplinary team, including the bariatric surgeon, obstetrician, dietitian, and nursing personnel. A program with a psychological professional is helpful for these patients as changes occurring with pregnancy may warrant additional one-on-one counseling (regarding fear of weight gain, anxiety, antepartum and postpartum depression, and other issues). The health team should openly collaborate as much as possible on the patient’s plan of care to achieve optimal outcomes for both mother and baby.
— Kathryn M. Lito, MPH, RD, LD, is the program dietitian for the University General Hospital bariatric program in Houston. She has been counseling weight loss surgery patients for more than two years, both preoperatively and postoperatively.
Table 1: Recommendations for Weight Gain During Pregnancy
Recommended Total Weight Gain (lbs)
28 to 40
25 to 35
15 to 25
— Reprinted with permission from Nutrition During Pregnancy: Part I: Weight Gain, Part II: Nutrient Supplements © 1990 by the National Academy of Sciences, courtesy of the National Academies Press, Washington, D.C.
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