Reproductive Concerns and Pregnancy after Bariatric Surgery: Practice Implications

Abstract

Approximately 113,000 bariatric procedures are conducted yearly. From 1998 to 2005, 83% of those having bariatric surgery in the 18 to 45-year-old age group were women. Reproductive implications are ideally addressed when surgery is planned, including the possibility of increased fertility after surgery, appropriate contraception, and the interval from surgery to pregnancy. Maternal and neonatal outcomes post bariatric surgery have generally been found to be positive and are often improved over those seen in obese women without a history of bariatric procedures. However, surgical complications have been reported, as well as nutritional deficits. Some studies have suggested an increase in small for gestational age (SGA) newborns and increased cesarean section rates, while others have not found these relationships. Neonatal complications have also been reported. Pregnancy care for women with a history of bariatric surgery includes screening for and managing nutritional deficits, careful assessment to rule out surgical complications, and attention to psychosocial needs. The aim of this article is to review findings of studies that examined the impact of bariatric procedures on fertility, contraception, pregnancy, and maternal and neonatal outcomes. In addition, the resulting implications for practice for all members of the healthcare team caring for women with a history of bariatric surgery, who are or may become pregnant, will be discussed.

Introduction

The management of pregnancy after bariatric surgery is a concern for both obstetric clinicians and those specializing in bariatric surgery. In 2007–2008, the National Health and Nutrition Examination Survey (NHANES) reported that the obesity rate for adults aged 20 and above was 33.8% (BMI ≥30 kg/m²), with 5.7% of subjects classified as extremely obese (BMI ≥40 kg/m²). Obesity rates increased for non-Hispanic white women (10.15%), non-Hispanic black women (11.4%), and Mexican-American women (9.8%) from the 1988–1994 NHANES survey to the 2007–2008 survey.¹ Bariatric surgery has been found to be the most effective treatment for obesity, considering the modest results realized by dietary changes and exercise due to the high rate of regained weight.²

There are approximately 113,000 cases of bariatric surgery performed per year. From 1998 to 2005, women comprised 83% of those having bariatric surgery in the 18 to 45-year-old age group. Between 2003 and 2005, more than 50,000 women aged 18 to 45 had bariatric surgery.³ Adverse pregnancy outcomes seen in pregnancies complicated by obesity are reduced for women following bariatric surgery, including: gestational diabetes mellitus (GDM), fetal macrosomia, and hypertensive disorders. However, postsurgical complications related to bariatric surgery have been reported during pregnancy.⁴ The aim of this paper is to review evidence from studies that examined reproductive issues after bariatric surgery and to provide a summary of practice implications.

Bariatric Procedures

There are a number of different types of bariatric surgery. The surgeries fall into three major categories: restrictive, malabsorptive, and procedures that have a component of both. Management considerations for the pregnant woman following bariatric surgery are influenced by the type of procedure that was performed. Restrictive surgeries include laparoscopic adjustable gastric banding (LAGB) and the vertical sleeve gastrectomy (VSG). The lap band procedure utilizes an adjustable silicone band that connects to an access port below the skin by thin, kink-resistant silicone tubing. A 30–50 mL gastric pouch is formed, which creates satiety with smaller amounts of food, limiting intake. The port allows for adjustment of the size of the band. Adding or removing saline to an inflatable balloon on the inner surface of the band makes it possible to change the size of the pouch based on individual dietary needs.⁵ Vertical banded gastroplasty (VBG) is performed using a band, as well as staples. The greater curvature of the stomach is reduced creating a narrow gastric sleeve.

The Roux-en-Y gastric bypass (RYGB) procedure combines restrictive and malabsorptive components and is the most commonly performed bariatric surgery in the United States.⁵ A small pouch in the upper portion of the stomach is created and the pouch is then anastomosed to the jejunum, bypassing the rest of the stomach and the duodenum. The RYBG procedure and other surgeries that have a malabsorptive component, such as the biliopancreatic diversion procedure or the biliopancreatic diversion with duodenal switch, create the greatest risk for the development of nutritional deficits.⁵

Preconception Care

For women of childbearing age, bariatric surgery planning should include a discussion of contraception choices and pregnancy planning. Reproductive implications of bariatric care should be addressed with women at the time surgery is first discussed and again postoperatively.⁶ Counseling and evaluation should be initiated before conception for women planning a pregnancy after bariatric surgery. Issues to be addressed include fertility, the interval between surgery and pregnancy, and contraception. Additionally, counseling regarding attempting pregnancy and the potential benefits and risks related to pregnancy after bariatric surgery should be discussed.

Fertility

Obesity is known to impact fertility negatively in women. Infertility is increased in obese women even when ovulation occurs. Mechanisms that may explain this are alterations in menstrual cycles (a longer follicular phase and shortened luteal phase), reduced levels of luteinizing hormone and follicle stimulating hormone, and elevated leptin. Leptin is an adipokine that is secreted by adipose tissue and affects fertility by inhibiting follicular growth.⁷

The incidence of polycystic ovary syndrome (PCOS) in adult women is at least 7% and is characterized by insulin resistance, hyperinsulinemia, excess androgens, hirsutism, as well as polycystic ovaries. Hyperandrogenism inhibits normal maturation of the follicle, and many women with PCOS experience oligo-ovulation or anovulation. More than half of patients with PCOS are overweight or obese.^7,8 Manifestations of PCOS, including abnormal hormonal levels and menstrual cycles, hirsutism, and anovulation, have been found to resolve after bariatric surgery.⁸ Less is known about the impact of weight loss after bariatric surgery in obese women who do experience ovulation. However, some improvement in luteal function and decreased leptin levels have been seen after surgery.^7,8

Studies regarding fertility after bariatric surgery are limited and the findings are conflicting. The majority of the studies examining this phenomenon failed to determine which subjects had been ovulatory or anovulatory before surgery, used convenience samples, were observational, or were not well controlled.⁴ Additionally, the American College of Obstetricians and Gynecologists (ACOG) clinical management guidelines addressing care of pregnant women following bariatric surgery state that surgery should not be considered a treatment for infertility.⁶ Regardless of the paucity of evidence, women of childbearing age should be advised that fertility may be increased after bariatric surgery. Contraceptive options should be addressed postoperatively. This is of particular importance when caring for adolescents, as pregnancy rates are higher for adolescents after bariatric surgery than for the general population of adolescent girls.⁹

Interval from surgery to pregnancy

Clinicians often recommend that women delay pregnancy until 12–24 months following bariatric surgery. This recommendation is due to the rapid weight loss that occurs during that time and the potential risk to the fetus. Additionally, it provides an opportunity for weight loss prior to pregnancy.⁶ However, the limited evidence that exists does not indicate that pregnancy occurring in the first year following surgery is associated with an increase in adverse pregnancy outcomes.

A retrospective study conducted in Israel compared pregnancy outcomes in a group of 104 women who conceived within the first year after various types of bariatric surgery to those of 385 women who conceived after the first year.¹⁰ The mean interval from surgery to conception for the group who conceived within the first year was 7±3.5 months; the mean interval for the group conceiving after the first 12 months was 15.5±3.7 months.

The two groups of women had similar characteristics. No significant differences were found in the BMI prior to surgery, pregnancy, and labor. Of interest is that fact that although there was an approximate 10 kg/m² point drop in the BMI for both groups, after surgery the women in both the shorter and longer interval groups were still considered obese, with a mean BMI >30 kg/m². This is consistent with other studies that have found that women who achieve pregnancies after bariatric surgery continue to be obese.¹¹

The only significant difference between the two groups was a higher incidence of LAGB in the group that conceived in the first year after surgery. The investigators found no other significant differences between the group who conceived in the first year following surgery and the group that conceived after the first year. Outcomes were equivalent between the groups in terms of complications of bariatric surgery, such as gastric band slippage, as well as complications of pregnancy, including hypertensive disorders, GDM, fetal growth restriction, and preterm labor. There were no significant differences in newborn outcomes and the rate of cesarean sections.¹⁰

When counseling women regarding timing of pregnancy after bariatric surgery, an individualized approach is warranted. The age of the woman and fertility history should be considered. Delaying pregnancy based on weight loss goals rather than a specific time interval may be appropriate based on current evidence. Regardless of recommendations regarding the interval between surgery and pregnancy, contraception should be addressed.¹²

Contraception

Providers often recommend against oral contraceptive (OC) use for women with a history of bariatric procedures with a malabsorptive component. It is common for women to be instructed to avoid OCs two months before and after surgery due to the increased incidence of postoperative venous thrombosis seen in this population.¹² ACOG recommends that women who have had bariatric procedures avoid OCs.⁵ Nonoral contraceptive methods such as the contraceptive patch and the contraceptive ring may be considered. However, there is conflicting evidence regarding the effectiveness of these methods for obese women. The greatest concern is with the contraceptive patch, with a greater failure rate reported in women with a weight ≥90 kg.¹³

A systematic review of the research regarding contraceptive safety and efficacy revealed little evidence that oral contraceptives are less effective after bariatric surgery.¹⁴ However, the few studies that investigated this are poor quality observational studies and two pharmacokinetic studies. The women in the pharmacokinetic studies had jejunoileal bypass, a surgery that is no longer performed. The two pharmacokinetic studies did demonstrate some malabsorption of the contraceptive hormones. The outdated jejunoileal bypass procedure caused greater malabsorption than surgeries that are currently performed.¹⁴ Although there is a lack of direct evidence demonstrating decreased effectiveness of OCs, the authors of the systematic review point out that procedures that cause malabsorption could potentially decrease OC effectiveness. The studies suggest that this risk is increased for women who experience long-term diarrhea and/or vomiting, which are both risks associated with malabsorptive surgeries.¹⁴

Depomedroxyprogesterone acetate (DMPA), also known as Depo-Provera, is a progestin-only contraceptive that is given by injection every 3 months. Some concerns regarding the use of DMPA following bariatric surgery have been raised regarding weight gain and reduced bone density.¹⁴ Decreased bone density has been found in users of DMPA. The Federal Drug Administration issued a black box warning regarding the potential for bone loss with use of the contraceptive.¹⁵ After bariatric surgery, bone loss may occur as well, particularly for women who have had a procedure that includes a malabsorptive component.¹⁴

Another progestin-only method that is nonoral is Implanon, a subdermal progestin implant. However, this method has not been studied in obese women.¹⁶ Intrauterine devices (IUD) provide a long-term alternative to oral and injectable contraceptives. The two IUDs available in the United States are the Copper T380A (Para-Guard) and the Levonorgestrel intrauterine system (Mirena) that releases progestin. The Para-Guard may be the best choice for women with a history of bariatric procedures, as there are reports of weight gain with use of the Mirena IUD.¹⁶

Nutrition

Ideally, nutritional deficits should be addressed prior to pregnancy for women with a history of bariatric surgery. However, the unintended pregnancy rate in the United States is >50%.¹⁷ Therefore, many women begin pregnancy without preconception care. When this occurs for women with a history of bariatric surgery, nutritional assessment should be initiated early in pregnancy, ideally at the first prenatal visit.¹⁸

When assessing the risk for nutritional deficits during pregnancy, it is important to consider the type of surgery performed, as this has an impact on potential nutritional deficits. Patients with a history of surgeries with a malabsorptive component face the greatest risk of nutritional deficiencies. Micronutrient deficits that are common include iron, B vitamins, including folate, calcium, and vitamin D.⁵

Iron

Iron deficiency anemia is seen in 12% to 47% of bariatric surgery patients, with menstruating and pregnant women at the greatest risk.⁵ The mechanisms that contribute to iron deficiency anemia include decreased food intake due to intolerance (particularly foods high in iron such as red meat), the bypass of the duodenum, and decreased exposure of food to gastric acidity.⁵ Gastric acid is required to release iron from foods and to convert iron to a form that can be absorbed.

The form of iron best tolerated after bariatric surgery is ferrous fumerate. This form is more easily tolerated and better absorbed than ferrous sulfate or ferrous gluconate, as it has already been broken down from the ferric state. Vitamin C taken at the same time as iron supplementation enhances the absorption of iron.¹⁹ Ensuring adequate iron during pregnancy is important, as iron deficiency anemia is associated with preterm delivery, low birth weight, and increased infant mortality.²⁰

B vitamins

The U.S. Preventative Services Task Force recommends a daily intake of 0.4–0.8 mg of folic acid for all women who are planning to become pregnant, or are capable of becoming pregnant, to prevent neural tube defects.²¹ The daily recommended allowance of folic acid for pregnant women is 0.6 mg.²² Low rates of folic acid deficiency have been found in the United States following bariatric surgery, which may be due to fortification of foods such as bread and cereal.⁵ Evidence does not exist regarding a need to exceed folic acid supplementation beyond the dose recommended in pregnancies not complicated by a history of bariatric surgery.⁶

Vitamin B12 deficiencies are associated with malabsorptive procedures. Approximately one third of patients after RYGB have been found to have vitamin B12 deficiency. However, the deficiency rate for patients who received supplementation was found to be only 4%.⁵ Vitamin B12 deficiency should be addressed for women of childbearing age at the time of surgery due to the risk for early pregnancy loss associated with this deficiency.

In the setting of vitamin B12 deficiency, homocysteine metabolism is altered, resulting in elevated levels of the amino acid. Hyperhomocysteinemia is a risk factor for thrombotic events and impaired placental vasculature. This process and increased pregnancy loss are usually seen in women with inherited thrombophilias. However, this may occur in women who have B vitamin deficiencies as well.¹⁸ Therefore, women should consume sufficient B vitamins prior to conception.

Vitamin B1 deficiency after bariatric surgery has been reported in patients with a history of gastric bypass procedures. Additionally, there are isolated reports of vitamin B1 deficiency in patients with restrictive procedures. The majority of cases reported occurred in patients who experienced hyperemesis. As hyperemesis is a common pregnancy complication, vigilance in screening for B1 deficiency and repletion if needed are important.⁵

Calcium and vitamin D

Calcium and vitamin D deficiency are common after bariatric surgery. In order to meet fetal needs for bone and teeth mineralization, a daily intake of 1,000 mg is recommended for women aged ≥19 and 1,300 mg/day for women aged <19.²³ If maternal calcium levels are low, fetal needs will be met while bone demineralization occurs for the mother. Additionally, calcium blood tests may be misleading, as calcium will be lost from the bones in order to maintain maternal calcium serum levels. A daily intake of 1,500 mg of calcium citrate is recommended for pregnant women with a history of gastric bypass.¹⁹ Calcium citrate should be prescribed rather than calcium carbonate, as it more easily absorbed in the setting of decreased exposure to stomach acid.²⁴

The Institute of Medicine (IOM) recommends 400 IUs of vitamin D daily for pregnant women with an upper limit of 4,000 IUs per day.²⁵ Vitamin D deficiency in the United States is estimated to affect 70% of Caucasians and 95% of African Americans. The incidence of deficiency is increased in overweight and obese individuals.²⁶ Supplementation should be based on the result of 25 (OH) D levels.²⁷ The IOM identifies vitamin D levels of ≥20 ng/mL as sufficient. However, many experts advocate for levels of ≥30 ng/mL.²⁷ As many women with a history of bariatric surgery remain obese at conception and during pregnancy, screening, repletion, and follow-up monitoring should be a component of the plan of care.⁶

ACOG advises the routine monitoring of the following every trimester: iron, ferritin, calcium, and vitamin D, with oral or parental supplementation as needed. Other recommendations include consideration of prenatal vitamins as well as a multivitamin. Consultation with a dietician will give the patient additional support in meeting the challenges of nutritional needs during pregnancy.⁶ Clinicians should assess patients eating habits and provide support and education based on the assessment. Patients may be advised to eat three to five small meals a day, eat slowly, chew food well, and avoid fluids 10 minutes before meals and 90 minutes afterwards.¹⁸

Weight gain

In the absence of evidence-based guidelines for the nutritional management of pregnancy following bariatric surgery, the IOM recommendations regarding weight gain during pregnancy may be followed (Table 1).²⁸ The guidelines recommend a weight gain for women with a BMI ≥30 kg/m² of 11–20 pounds. The IOM recommends one weight gain range for all women with a prepregnancy BMI ≥30 kg/m² regardless of the severity of obesity. Although the report recommends less weight gain for obese women than the 1990 report (that advocated a weight gain of ≥15 pounds), research findings suggest that pregnancy weight gain less than the range recommended by the IOM, or weight loss during pregnancy, may improve perinatal outcomes.²⁹ Studies conducted after the 2009 guidelines were introduced have examined the impact of weight gain on birth outcomes for women with various BMIs.

Table 1.

IOM Recommended Weight Gain During Pregnancy

Weight category	Body mass index (BMI)	Range for recommended weight gain	Rate of weight gain in the second and third trimester
Underweight	<18.5 kg/m²	28–40 lbs	1.0–1.3 lbs
Normal	18.5–24.9 kg/m²	25–35 lbs	0.8–1 lbs
Overweight	25–29.9 kg/m²	15–25 lbs	0.5–0.7 lbs
Obese	>30.0 kg/m²	11–20 lbs	0.4–0.6 lbs

Adapted from Institute of Medicine.²⁸

IOM, Institute of Medicine.

In a population-based cohort study conducted in Sweden, Bloomberg examined birth outcomes for obese women using the following World Health Organization categories: class I (BMI of 30.0–34.9 kg/m² ), class II (BMI of 35.0–35.9 kg/m² ), and class III (BMI of ≥40 kg/m²) (Table 2).²⁹ The researcher found that the risk for cesarean delivery, large for gestational age infants, preeclampsia, and fetal distress was decreased for women in all three categories who lost weight during pregnancy, compared to women who gained the recommended 11–20 pounds. Women who lost weight during pregnancy had an increased risk of small for gestational age (SGA) infants. Women in obesity class I and II with low weight gain (0–11 pounds) had an increase in SGA infants as well. However, the women in obesity class III with low weight gain did not have an increase in delivery of SGA newborns.

Table 2.

WHO Obesity Classifications

Weight category	Body mass index (BMI)
Obesity Class I	30.0–34.9 kg/m²
Obesity Class II	35.0–35.9 kg/m²
Obesity Class III	≥40 kg/m²

Adapted from Bloomberg.²⁹

WHO, World Health Organization.

In another population-based study using Centers for Disease Control data, Hinkle et al. found that women in obesity class I with no weight gain or weight loss had a significant increase in SGA infants.³⁰ However, weight gain below the IOM recommendations did not result in a significant increase in the delivery of SGA infants. For women in obesity classes II and III, a weight loss of >11 pounds was associated with an increase in SGA; weight loss <11 pounds to a weight gain of 10.8 pounds was associated with no significant increase in SGA infants and a decrease in macrosomia (birth grams weight ≥4,500 grams).

The authors concluded that for women with a BMI ≥35 kg/m², weight gain less than the 2009 IOM recommendations may avoid macrosomia without an increase in SGA. Many women begin pregnancy with a BMI ≥30 kg/m² following bariatric surgery. Advice regarding appropriate weight gain may be individualized, based on the prepregnancy BMI.

Adjustment of gastric bands during pregnancy

Women with a history of LAGB procedures may have the band adjusted to relieve nausea and vomiting during the first trimester.⁶ In an investigation by Martin et al. of 18 pregnancies, three women had fluid removed from the band due to nausea and vomiting.³¹ Two women had all of the fluid removed prophylactically and subsequently gained an excessive amount of weight. ACOG states that although consensus regarding active band management during pregnancy has not been reached, consultation early in pregnancy with the bariatric surgeon is advised.⁶

Obstetric Outcomes

The literature regarding perinatal outcomes following bariatric surgery suggests that risk for maternal complications is lower in women postsurgery than in obese women. Additionally, research findings indicate improved neonatal outcomes in this population. However, studies examining pregnancy after bariatric surgery are primarily retrospective studies and case reports with small sample sizes. The lack of randomized controlled trials and heterogeneity in terms of control groups in the existing studies make it difficult to generalize findings.⁴

In a systemic review, Maggard et al. examined 75 studies, including case reports, case series, cohort studies, and matched cohort studies.⁴ Studies compared the obstetric outcomes for women who had pregnancies postsurgery to obese controls without surgery. Other studies compared pregnancy outcomes for women after bariatric surgery to perinatal outcomes of a cohort of women prior to undergoing bariatric procedures. The studies suggest that women with a history of LAGB had lower rates of GDM and preeclampsia. Pregnancy-induced hypertension was found to be unchanged or lower in the postsurgical group.

In a retrospective review of birth logs, a group of 26 women with pregnancies following RYGB surgery were compared to a control group of 254 women. The mean BMI for the postsurgical group was 32.5 kg/m²±7.2. The investigators stratified the control group by BMI: 74.0% were nonobese, 15.3% were obese, and 10.6% were morbidly obese. No significant difference in pregnancy complications, including GDM, preeclampsia, and pregnancy-induced hypertension, between the RYGB group and controls was found, regardless of obesity status in the controls. Two complications that were significantly higher in the RYBG group versus the nonobese group were anemia (p=0.001) and SGA (p<0.001). Macrosomia was significantly increased in the morbidly obese controls as compared to the RYGB group.³²

Evidence does not suggest a strong relationship between cesarean section rates and a history of bariatric procedures.⁴ Patel et al. found cesarean section rates in women after bariatric surgery were significantly higher than in nonobese controls, and not significantly different from the obese and morbidly obese controls.³² Weintraub et al. found a significantly higher cesarean rate when comparing a group of 507 deliveries following bariatric surgery to deliveries of a control group of 301 women who delivered before surgery. However, when the higher rate of previous cesarean sections was controlled for in the postsurgery group, the relationship was not significant.³³

Bebber et al. performed a retrospective study of 39 pregnant women who had undergone previous RYGB surgery.³⁴ The investigators found the subjects had a higher rate of cesarean delivery. However, they concluded that the women were still obese at the time of the pregnancy, which is a risk factor for cesarean delivery. The ACOG practice bulletin states that bariatric surgery is not an indication for cesarean section.⁵

Surgical Complications

Complications related to bariatric surgery have been reported in subsequent pregnancies. Complications include intestinal hernias, abdominal wall hernias, bowel obstruction, cholelithiasis, hyperemesis, and band erosion or migration.³⁵ Maggard et al. found 20 reported complications during pregnancy that required surgical intervention. Complications identified included 14 bowel obstructions, one gastric ulcer, one staple line stricture, and four band-related complications, with the complications occurring between 13 and 37 weeks gestational age. There were five neonatal and three maternal deaths in this group of patients. It is important to note that the majority of these women presented with vague abdominal complaints that are common during pregnancy. Treatment delays occurred in 7 of the 20 cases reported.⁴ Surgical complications should be considered in women presenting with the following symptoms: nausea, vomiting, abdominal pain, heartburn, and uterine cramping.³⁵

The reported incidence of intestinal obstructions after RYGB surgery is as high as 5%.³⁶ Causes of obstruction are the increased intra-abdominal pressure that occurs during pregnancy with the resulting shift in abdominal organs and adhesions from prior surgery. Intestinal obstructions are most commonly seen in mid-pregnancy, at the time of delivery during descent of the fetal head, and postpartum due to the rapid involution of the uterus.^35–37 Symptoms such as nausea, vomiting, epigastric discomfort, abdominal pain, and uterine cramping should be thoroughly assessed and evaluated. Imaging or exploratory laparotomy may be indicated.³⁵

Complications may also occur for patients with a history of restrictive procedures. The complications include gastric band slippage or migration, esophageal and gastric pouch dilatation, stomal obstructions, and erosion of the band into the stomach. Problems associated with the access port or tubing, such as leakage, may occur as well.³⁸ Band erosion and migration present with symptoms of intermittent nausea, vomiting, and complaints of abdominal pain.⁶

Newborn Outcomes

Research findings indicate that a history of bariatric surgery does not have a negative impact on neonatal outcomes, with the exception of some rare complications. In the systematic review by Maggard et al., the most commonly identified neonatal outcomes were birth weight, preterm delivery, and perinatal mortality. The authors reviewed 11 studies that compared neonatal outcomes to a control group.⁴

Neonatal birth weight is known to be impacted by maternal BMI; obese women are more likely to have macrosomic infants.³⁹ Of the 11 studies reviewed by Maggard et al., seven compared rates of macrosomia for infants born to women after bariatric surgery to control groups. Macrosomia was lower in the women who had a history of bariatric surgery in six studies, with statistical significance in all but one.⁴ In a population-based study, the rate of macrosomia was significantly higher in the bariatric group than in the control group. The relationship was still found after BMI was controlled for in the comparison group.⁴⁰

Results are mixed regarding the impact of bariatric surgery on SGA or low birth weight (weight <2,500 grams). In a retrospective review, the incidence of newborns found to be SGA diagnosed during pregnancy was significantly higher in women with a history of RYGB procedures, as compared to nonobese women (11.5%, p=<.0001). No significant difference was observed in women with a history of RYGB surgery when compared with newborns of obese or severely obese women.³² After delivery, it was found that the infants of the women with a history of RYGB were not SGA. The investigators attributed this finding to the limitations of ultrasound when used with obese and severely obese women.

Ducarme et al. compared outcomes of newborns delivered by obese women with a history of LAGB to a group of newborns delivered by a group of obese women without a history of surgery. A lower rate of low birth weight was found in the neonates in the post bariatric surgery group (7.7%) versus controls (10.6%, p<0.05).⁴¹ However, other studies found no significant differences in SGA rates of patients who had bariatric procedures versus controls.^42,43 Additionally, perinatal mortality and preterm labor rates have not been found to be increased after bariatric surgery.^4,32–44

There is some anecdotal evidence that malabsorption of micronutrients, in particular vitamin K, can lead to intracranial hemorrhage in the infants of women with a history of bariatric procedures.⁴⁵ In three of five cases reviewed, the infants died after delivery, and the two who lived had significant morbidity. The vitamin K levels of the mothers were quite low, resulting in intracranial bleeding that is associated with vitamin K deficiency. Weintraub et al.'s multivariate analysis indicated that bariatric surgery is not an independent risk factor for fetal malformation.³³ Maggard's systematic review suggested an increase in neural tube defects in women not adherent to vitamin supplementation.⁴

Postpartum

Lactation

ACOG recommends careful monitoring of breastfed infants, as nutritional deficits have been reported.⁶ Breast milk may be affected by micronutrient deficiencies, especially in women with a history of RYGB surgery or other bariatric procedures that have a malabsorptive component. Vitamin B12 deficiency in breastfed infants of women who had a history of bariatric procedures has been reported.^46–48 Additionally, fat malabsorption post bariatric surgery can cause breast milk to be lower in fat and calories, leading to poor neonatal growth.⁴⁹ Nutritional monitoring during pregnancy and lactation for both mothers and infants is warranted.

Postpartum pain management

An additional concern is postpartum pain management. Nonsteroidal anti-inflammatory drugs (NSAIDs), although commonly used postpartum, should be avoided in women with a history of bariatric procedures. NSAIDs are thought to be a potential cause of anastomotic ulcers.¹⁹ Acetaminophen is an alternative to NSAIDS for the treatment of mild postpartum pain. Nonpharmacological interventions include topical applications and icepacks.⁵⁰

Practice Issues

Screening and diagnosis of GDM

Screening all pregnant women for GDM is recommended by ACOG. Risk factors for GDM include obesity, increased age, ethnicity, a family history of diabetes, and a history of GDM in a prior pregnancy. GDM is associated with maternal risks, including cesarean delivery, preeclampsia, and the development of type 2 diabetes. Newborn risks include macrosomia, shoulder dystocia, birth injuries, hypoglycemia after birth, hyperbilirubinemia, respiratory distress syndrome, and the development of childhood obesity. ACOG recommends screening by addressing patient history, clinical risk factors, or with a 1-hour 50-gram glucose challenge test (GCT).⁵¹

The American Diabetes Association (ADA) 2011 Clinical Practice Recommendations state that women with risk factors for diabetes (Table 3) should have early pregnancy screening at the initial prenatal visit using standard diagnostic criteria for diagnosing diabetes. In the past, a diagnosis of overt diabetes was not made at any time during pregnancy in a patient not previously diagnosed. The guidelines now state that if diabetes is found in early pregnancy, a diagnosis of overt diabetes instead of GDM should be made.⁵²

Table 3.

Risk Factors for First Trimester Pregnancy Screening for GDM

BMI>25 kg/m² with additional risk factors

Family history of diabetes

High-risk ethnic group

Women with PCOS

History of gestational diabetes or delivery of an infant >9 lbs

Clinical findings associated with insulin resistance such as severe obesity or acanthosis nigricans

Presence of glycosuria

Adapted from ADA Clinical Practice Recommendations 2011.⁴⁹

GDM, gestational diabetes mellitus; PCOS, polycystic ovary syndrome; ADA, American Diabetes Association.

The ADA recommends that all women receive screening for GDM between 24 and 28 weeks gestation. Additionally, if women screened early for risk factors are not found to have diabetes, screening is repeated at 24–28 weeks gestation. ACOG recommends screening with a two-step process using a 1-hour 50-gram GCT initially and a 3-hour 100-gram oral glucose tolerance test (OGTT) for those who exceed the critical value of 140 mg/dL. The ADA recommends a one-step process using a 2-hour 75-gram OGTT (see Table 4).⁵² Patients with a history of restrictive procedures such as LAGB or VSG may be screened with glucola (used for GCTs and OGTTs).⁶

Table 4.

Diagnostic Criteria for GDM

	ACOG Diagnostic Guidelines
	Two-step method	ADA Diagnostic Guidelines
	1-hour 50-gram screening test, if >140	One-step method
	3-hour 100-gram OGTT	2-hour 75-gram OGTT
Test	Requires two abnormal values	Requires one abnormal value
Fasting plasma glucose	>95 mg/dL	≥92 mg/dL
1-hour plasma glucose	>180 mg/dL	>180 mg/dL
2-hour plasma glucose	>155 mg/dL	>153 mg/dL
3-hour plasma glucose	>140 mg/dL

Adapted from and American College of Obstetricians and Gynecologists⁵¹ and ADA Clinical Practice Recommendations 2011.⁵²

ACOG, American College of Obstetricians and Gynecologists; OGTT, Oral glucose tolerance test.

Women with a history of procedures with a malabsorptive component such as RYBG should not be screened with oral glucola. These patients are at increased risk for dumping syndrome, which is increased with the use of oral glucola.⁶ An alternative method used to assess for GDM is self-blood-glucose testing in the home. The patient records the fasting and 1-hour postprandial blood glucose values for 1 week, sometime between 24 and 28 weeks gestation. In addition, A1C tests may be used in this population.⁵³ As many women with a history of bariatric surgery begin pregnancy overweight or obese, screening for and management of GDM are important aspects of care.

Psychosocial issues

Women with histories of bariatric procedures may have experienced depression and body image disturbances as well as eating disorders prior to surgery.^19–54 A thorough discussion of the psychosocial implications of pregnancy after bariatric surgery is outside of the scope of this article. It is, however, essential to address this aspect of care. Assessment of the patient's response to the pregnancy and thoughts regarding weight gain during pregnancy should be initiated at the beginning of the pregnancy. Additionally, ongoing assessment regarding the patient's mood and feelings about the pregnancy should be revisited at all prenatal visits. Referral to a mental health professional may be considered if problems are discovered.

Conclusion

Pregnancy following bariatric surgery has generally been found to be safe, and the adverse outcomes seen with obesity are often decreased. Reproductive issues including fertility, contraception, and the timing of pregnancy should be part of the discussion during the planning of bariatric surgery for women of childbearing age. If pregnancies are planned, nutritional deficits can be addressed and weight loss goals met prior to pregnancy.

Although the evidence regarding obstetric outcomes following bariatric pregnancy is encouraging, complications may occur. Careful ongoing assessment and attention to complaints, even those common during pregnancy, can avoid delays in diagnosis and treatment. The care of pregnant women with a history of bariatric surgery is best addressed with a collaborative approach involving the patient's bariatric team and the obstetric team.

Footnotes

Disclosure Statement

No competing financial interests exist.

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