The Influence of Pregnancy on Weight Loss After Previous Bariatric Surgery

Abstract

Introduction:

Bariatric surgery is routinely performed on obese women of reproductive age, most commonly with the laparoscopic sleeve gastrectomy (SG) and Roux-en-Y gastric bypass procedures (RYGB). This study analyzes the effects of postoperative pregnancy on excess BMI loss percentage (EBMIL%) after SG and RYGB.

Methods:

A retrospective study was conducted with 191 female patients of reproductive age between 20 and 40 years who underwent SG and RYGB performed at our institution between January 2017 and December 2018. A comparison of the results at 4-year follow-up was performed between patients who became pregnant after bariatric surgery with patients who did not.

Results:

Among 191 total cases, 32 (16.7%) patients became pregnant within a 4-year follow-up period, and 159 (83.2%) patients did not. The median postoperative body mass index (BMI) in the pregnant group was 33.3 kg/m² (interquartile range [IQR] 30.1–38.5) and 33.5 kg/m² (IQR 28.9–38.6) in the nonpregnant group. The mean EBMIL% within a 4-year follow-up in the pregnant group was 50.4% (standard deviation [SD] 23.5) and 55.5% (SD 30.4) in the nonpregnant group. The median weight before surgery in the pregnant group was 112 kg (IQR 107.9–132.2) and 117 kg (IQR 106–132.5) in the nonpregnant group. The median weight after surgery in the pregnant group was 89.5 kg (IQR 79.5–111) and 88.9 kg (IQR 78–103) in the nonpregnant group. There was no significant difference between outcomes.

Conclusion:

Weight loss maintenance after bariatric surgery is not impacted by postoperative pregnancy within a 4-year follow-up after SG and RYGB.

Introduction

Obesity, defined as a body mass index (BMI) >30 kg/m², is a chronic and common disease in today's world, affecting 41.9% of U.S. adults between 2017 and 2020.¹ Its prevalence has steadily increased, specifically within the female population.² Severe obesity, defined as a BMI >40 kg/m², affects 9.2% of U.S. adults, with a higher prevalence in women (11.5%) compared with men (6.9%).³ Bariatric surgery has proven to be the most effective weight loss method compared with medical therapy.⁴ Women constitute the majority of patients undergoing bariatric surgery, and most of these women are of reproductive age.⁵

Obesity is present in ∼10% of pregnant women.⁶ Bariatric surgery can help patients lose weight before pregnancy, which in turn reduces maternal and fetal complications, and improves fertility.⁷ Studies have shown that obese women who become pregnant have a tendency to gain excess gestational weight. Excess gestational weight gain is a known risk factor for postpartum weight retention and obesity later on in life.⁸

Laparoscopic Roux-en-Y gastric bypass procedures (RYGB) and sleeve gastrectomy (SG) are the most commonly performed types of bariatric surgery in the United States. Postoperative bariatric patients have a mean weight loss of 33% of initial body weight after successful surgery. However, at least one-third of patients will regain over 25% of their total weight loss within 2 to 5 years postoperatively.⁹ Surgical success and/or failure can be assessed by determining excess BMI loss percentage (EBMIL%), which is calculated based on an ideal BMI of 25 kg/m².¹⁰ Surgical failure after bariatric surgery is defined as maintaining <50% of excess weight loss over 18 to 24 months or a BMI >35.¹¹ This can be attributed to either insufficient weight loss or weight regain postoperatively. Common predictors of insufficient weight loss and weight regain after bariatric surgery include dietary nonadherence, physical inactivity, mental health issues, and anatomic surgical failure.¹² Given that pregnancy can increase the risk of obesity in postpartum patients, it may be a potential contributor to weight regain after bariatric surgery.

The objective of our study is to assess the impact of pregnancy on maintaining weight loss after bariatric surgery, particularly in laparoscopic RYGB and SG.

Methods

Study design

The Metabolic and Bariatric Surgery Accreditation Quality Improvement Program (MBSAQIP) Data Registry is a prospectively collected database, with innumerous variables, such as patient demographic characteristics, perioperative information, and postoperative morbidity and mortality data. In our study, we assessed our center data for laparoscopic SG and RYGB from the MBSAQIP from January 2017 to December 2018. We included for analysis all female patients with morbid obesity (BMI >35 kg/m² with comorbidities or BMI >40 kg/m²) of reproductive age (between 20 and 40 years) who underwent laparoscopic SG or RYGB. We excluded patients who did not have 4-year follow-up, revisions, conversions, and patients who were currently pregnant. All patients were evaluated by a multidisciplinary team preoperatively. At our institution's bariatric program, we recommend patients to postpone pregnancy until after 2 years postsurgery, in accordance with the The American College of Obstetricians and Gynecologists guidelines.¹³

Rapid weight loss is expected the first year and a half after surgery, and becoming pregnant during this time can lead to adverse pregnancy outcomes.

We chose to analyze patient outcomes after a 4-year follow-up period, to allow for a sufficient amount of time for postoperative patients to become pregnant.

Data collection

Data were collected and divided in sections: patient characteristics, surgical technique, 4-year follow-up outcomes, and pregnancy-related complications. Baseline demographics included age, BMI, American Society of Anesthesiologists (ASA) class, surgical approach (laparoscopic SG or RYGB), smoking status, diabetes mellitus (DM), hypertension (HTN), chronic obstructive pulmonary disease (COPD), obstructive sleep apnea (OSA), myocardial infarct, cerebrovascular accident (CVA), hyperlipidemia (HLD), use of anticoagulants, and gastroesophageal reflux disease (GERD).

Preoperative and postoperative data were collected for all patients: presence of pregnancy after bariatric surgery, median weight before surgery, median BMI before surgery, surgical approach, date of last follow-up visit, median weight at 4-year follow-up visit, and mean BMI at 4-year follow-up visit.

For the group of patients who became pregnant postoperatively, we collected additional data regarding any pregnancy-related complications. This included any newly diagnosed disorders in the mother during pregnancy or fetal conditions during birth.

Statistical analyses

Categorical variables were presented as frequencies and percentages. Continuous variables whose distribution approximated normality were reported as mean and standard deviation (SD), and those with skewed distributions were reported as median and interquartile range (IQR). Univariate analyses were performed using Pearson chi-square test for categorical variables and the Kruskal–Wallis test for continuous variables. A P value <.05 was considered significant. Data were analyzed using the SPSS v.29 (SPSS, Inc., Chicago). Approval for this study was obtained through the Institutional Review Board (IRB 2022-13755) and all Health Insurance Portability and Accountability Act (HIPAA) procedures were followed.

Results

A total of 191 female patients of reproductive age underwent laparoscopic SG or RYGB in our academic center between January 2017 and December 2018. Out of these patients, 32 (16.7%) became pregnant within a 4-year follow-up period and 159 (83.2%) did not. Mean age in the pregnant patients was 29 years (IQR 26–33) with a mean preoperative BMI of 43 kg/m² (IQR 39.9–48.2). In the nonpregnant patients, the mean age was 31 years (IQR 28–34) with a mean preoperative BMI of 43.7 kg/m² (IQR 30.7–48.4). Most patients were ASA II (14; 44% in the pregnant group, 71; 45% in the nonpregnant group) or ASA III (18; 56% in the pregnant group, 88; 55% in the nonpregnant group).

In terms of surgical technique, 23 (72%) pregnant patients underwent SG while 9 (28%) underwent RYGB. Out of the nonpregnant patients, 136 (86%) underwent SG while 23 (14%) underwent RYGB. HTN was present in 4 (13%) pregnant patients and 28 (18%) nonpregnant patients. DM was present in 8 (25%) pregnant patients and 13 (8%) nonpregnant patients. CVA was present in 0 (0%) pregnant patients and 2 (1.2%) nonpregnant patients. COPD was present in 0 (0%) pregnant patients and 1 (0.6%) nonpregnant patients. GERD was present in 6 (19%) pregnant patients and 40 (25%) nonpregnant patients. OSA was present in 5 (16%) pregnant patients and 22 (14%) nonpregnant patients. HLD was present in 2 (6%) pregnant patients and 21 (13%) nonpregnant patients. The use of anticoagulation was present in 2 (6%) pregnant patients and 1 (0.6%) nonpregnant patients. Out of the pregnant patients, 9 (28%) were classified as former smokers and 0 (0%) were classified as current smokers. Out of the nonpregnant patients, 26 (16%) were classified as former smokers and 4 (2.5%) were classified as current smokers. Patient characteristics are as listed in Table 1.

Table 1.

Patient Characteristics

	Pregnant, n = 32	Nonpregnant, n = 159	P
Age, median (IQR)	29 (26–32.8)	31 (28–34)	.343
BMI preop, kg/m², median (IQR)	43.2 (39.9–48.2)	43.7 (40.7–48.4)	.583
ASA			.542
II	14 (43.8)	71 (44.7)
III	18 (56.3)	88 (55.3)
Surgical technique			.057
Sleeve	23 (71.9)	136 (85.5)
Gastric bypass	9 (28.1)	23 (14.5)
Hypertension	4 (12.5)	28 (17.6)	.34
Diabetes mellitus	8 (25)	13 (8.2)	.011
CVA	0	2 (1.2)	.816
Smoking status			.212
Former	9 (28.1)	26 (16.4)
Current smoker	0	4 (2.5)
COPD	0	1 (0.6)	.832
GERD	6 (18.8)	40 (25.2)	.299
OSA	5 (15.6)	22 (13.8)	.487
HLD	2 (6.3)	21 (13.2)	.216
Anticoagulation use	2 (6.3)	1 (0.6)	.073

ASA, American Society of Anesthesiologists; BMI, body mass index; COPD, chronic obstructive pulmonary disease; CVA, cerebrovascular accident; GERD, gastroesophageal reflux disease; HLD, hyperlipidemia; IQR, interquartile range; OSA, obstructive sleep apnea.

The median post-op BMI in the pregnant group was 33.3 kg/m² (IQR 30–38.5) and 33.5 kg/m² (IQR 28.9–38.6) in the nonpregnant group. The mean EBMIL% within a 4-year follow-up in the pregnant group was 50.4% (SD 23.5) and 55.5% (SD 30.4) in the nonpregnant group. The median weight before surgery in the pregnant group was 112 kg (IQR 107.9–132) and 117 kg (IQR 106–132) in the nonpregnant group. The median weight after surgery in the pregnant group was 89.8 kg (IQR 79.5–111) and 88.9 kg (IQR 78–103) in the nonpregnant group. There was no significant difference between the groups when comparing these outcomes. The 4-year follow-up outcomes are listed in Table 2.

Table 2.

Outcomes at 4-Year Follow-Up

	Pregnant, n = 32	Nonpregnant, n = 159	P
BMI postop, kg/m², median (IQR)	33.3 (30.1–38.5)	33.5 (28.9–38.6)	.872
EBMIL%, mean (SD)	50.4 (23.5)	55.5 (30.4)	.371
Weight before surgery, kg, median (IQR)	112.7 (107.9–132.2)	117 (106–132.5)	.086
Weight after surgery, kg, median (IQR)	89.5 (79.5–111)	88.9 (78–103)	.872

BMI, body mass index; EBMIL%, excess body mass index loss percentage; IQR, interquartile range; SD, standard deviation.

Out of the 32 patients who became pregnant postoperatively, 3 were followed at outside hospitals during pregnancy and childbirth. Therefore, pregnancy-related complications and delivery dates of these patients could not be evaluated within our electronic medical records. A total of 29 patients were followed at our institution during their pregnancy: 1 patient gave birth within 1 year postoperatively, 9 patients within 1 and 2 years postoperatively, 10 patients within 2 and 3 years postoperatively, and 9 patients gave birth within 3 and 4 years post-operatively. Out of these 29 patients, 6 (19%) patients developed gestational hypertension (GHTN). Gestational diabetes mellitus (GDM) occurred in 4 (12.5%) patients. Anemia developed in 4 (12.5%) patients. Group B Streptococcus infection occurred in 2 (6.2%) patients. Preterm premature rupture of membranes occurred in 1 (3.1%) patient. Late-term induction of labor occurred in 1 (3.1%) patient. Pre-eclampsia developed in 1 (3.1%) patient. Chorioamnionitis developed in 1 (3.1%) patient. Fetal bradycardia developed in the fetus of 1 (3.1%) patient. There was 1 (3.1%) patient who gave birth to twins. These pregnancy-related complications are listed in Table 3.

Table 3.

Pregnancy-Related Complications in Postoperative Bariatric Patients

	Pregnant (n = 32), n (%)
GHTN	6 (18.8)
GDM	4 (12.5)
Anemia	4 (12.5)
GBS	2 (6.2)
PPROM	1 (3.1)
LT IOL	1 (3.1)
Pre-eclampsia	1 (3.1)
Twins	1 (3.1)
Fetal bradycardia	1 (3.1)
Chorioamnionitis	1 (3.1)

GBS, group B Streptococcus; GDM, gestational diabetes mellitus; GHTN, gestational hypertension; LT IOL, late term induction of labor; PPROM, preterm premature rupture of the membranes.

Discussion

There has been limited data looking into the relationship between pregnancy and bariatric surgery. Since most bariatric patients are females of reproductive age, we wanted to investigate how weight loss in this population pool was affected after giving birth. Our results show that pregnancy has no impact on weight loss after bariatric surgery, with no significant difference in EBMIL% between pregnant patients and nonpregnant patients at 4-year follow-up.

In reviewing the relevant literature, most studies also demonstrated no significant difference in weight loss between pregnant and nonpregnant patients after bariatric surgery.^14–18 Courcoulas et al. published the Longitudinal Assessment of Bariatric Surgery (LABS) study, which is a three-phase prospective, multicenter, observational cohort study and comprises one of the first National Institutes of Health studies focusing on bariatric surgery. Harrod et al. (2020) used data from the LABS-2 study and created a linear regression to look at percent change in total body weight over a 5-year follow-up period in females of reproductive age who underwent RYGB or laparoscopic adjustable gastric banding (LAGB) between 2006 and 2009 throughout 10 hospitals across the United States. Out of the 727 women of reproductive age, 80 (11%) became pregnant. The authors found no significant difference in percent change in total body weight between women who became pregnant and those who did not during a 5-year follow-up period.

Brönnimann et al. found that EBMIL% was similar in pregnant and nonpregnant bariatric patients at 5-year follow-up. This retrospective study compared weight loss and surgical complications in 287 female patients of reproductive age from 2010 to 2017 who underwent RYGB. Although patients in the pregnant group (n = 40) were significantly heavier and younger at the time of surgery, the EBMIL% as well as surgical complications were similar to the nonpregnant patients (n = 247) postoperatively. Similarly, Rottenstreich et al. found no effect of pregnancy on weight loss after bariatric surgery. This cross-sectional case–control study compared 80 females who became pregnant after SG to 80 females who did not become pregnant after SG and found no significant difference in excess weight loss (EWL%) at 5-year follow-up. Quyên Pham et al. was a retrospective study, which suggested that pregnancy after bariatric surgery may slow down weight loss early on, but has no effect on longer term weight loss. They looked at 591 women who underwent LAGB surgery or RYGB and compared outcomes at 2- and 5-year follow-up between patients who became pregnant after surgery (n = 84) and those who did not (n = 507).

While the pregnant patients had significantly greater EWL% at 2-year follow-up, they did not have a significant difference at 5-year follow-up. While our research had comparable outcomes to the aforementioned studies, we included SG in addition to RYGB, thus providing a more comprehensive and relevant review in light of today's most commonly performed bariatric procedures.

Few studies have found a significant impact of pregnancy on weight loss after bariatric surgery.^7,19,20 Froylich et al. compared 62 patients who were pregnant within 3 years before or after bariatric surgery with 92 patients who had never conceived and found excess EWL% in the delivery group before surgery. They concluded that pregnancy before surgery had a more negative effect on weight loss compared with those patients who had never been pregnant. Dao et al., compared pregnancy outcomes in those who became pregnant <1 year after bariatric surgery (early group, n = 21) with those who became pregnant more than 1 year after bariatric surgery (late group, n = 13). The late group had a significantly lower mean BMI at pregnancy compared with the early group, suggesting that women becoming pregnant shortly after surgery had not yet stabilized their weight.

When analyzing pregnancy-related complications in patients who had bariatric surgery, there were relatively few with major conditions impacting maternal or fetal health. Many studies have shown that bariatric surgery can reduce obesity-related complications in pregnancy.^21,22 Balestrin et al. was a retrospective study that looked at the impact of bariatric surgery on gestational outcomes. They found a lower occurrence of GHTN and GDM in pregnant women who had bariatric surgery (n = 93) compared with obese pregnant women (n = 205). There was no difference in frequency of prematurity, delivery methods, or postpartum complications. The weight difference between the newborns in either group was not statistically significant. Similarly, Alamri and Abdeen reviewed 139 studies and found that bariatric surgery reduced obesity-related complications during and after pregnancy. However, they did note that bariatric surgery before pregnancy may lead to certain adverse outcomes, including low birthweight and small-for-gestational-age infants. In addition, they found that maternal complications such as anemia and nutritional malabsorption were more likely when pregnancy occurred less than a year postoperatively.

Limitations of the study

Our study had several important limitations. This is a single-center and retrospective cohort study. Due to our small sample size, we may not have had the proper power to show a significant difference in EBMIL% if one did exist. Longer term effects of pregnancy on weight loss after bariatric procedures should also be evaluated, possibly looking into 10-year follow-up. Our study did not differentiate between weight loss after laparoscopic SG compared with RYGB. Future studies should stratify between the different surgical approaches to see if either has a significant difference on weight loss maintenance or pregnancy-related complications. Additionally, our study has inherent selection bias and attrition bias, given the fact that we did not include patients lost to 4-year follow-up, patients with multiple bariatric procedures, such as conversions to RYGB or revisions, and patients who became pregnant after surgery but were followed at another institution. These patients were excluded from our study.

Conclusion

We found that the mean EBMIL% within a 4-year follow-up after laparoscopic SG and RYGB had no significant difference between patients who became pregnant postoperatively and patients who did not. This provides more evidence to the limited existing literature showing that weight loss after bariatric surgery is not negatively affected by pregnancy.

Footnotes

Authors' Contributions

Study design: D.C., R.B., D.L.L., and V.K. Data collection and analysis: R.B., D.L.L., M.S., V.V., and R.S. Article preparation and editing: R.B., D.L.L., M.S., V.V., and D.C.

Disclosure Statement

No competing financial interests exist.

Funding Information

No funding was received for this article.

References

Division of Nutrition, Physical Activity, and Obesity, National Center for Chronic Disease Prevention and Health Promotion. Defining Adult Overweight & Obesity. Center for Disease Control and Prevention; June 3, 2022. Available from: https://www.cdc.gov/obesity/basics/adult-defining.html#print [Last accessed: May 1, 2023].

Kaska

, Kobiela

, Abacjew-Chmylko

, et al. Nutrition and pregnancy after bariatric surgery. ISRN Obes, 2013; 2013:492060; doi: 10.1155/2013/492060

Park

, Cheryl

. Overweight & Obesity Statistics. National Institute of Diabetes and digestive and Kidney Diseases. 2012. Available from: https://www.niddk.nih.gov/health-information/health-statistics/overweight-obesity#:~:text=About%201%20in%2011%20adults%20%289.2%25%29%20have%20severe,percentage%20of%20men%20who%20have%20severe%20obesity%20%286.9%25%29 [Last accessed: September 2021].

Maciejewski

, Arterburn

, Van Scoyoc

, et al. Bariatric surgery and long-term durability of weight loss. JAMA Surg, 2016; 151(11):1046–1055; doi: 10.1001/jamasurg.2016.2317

Różańska-Walędziak

, Bartnik

, Kacperczyk-Bartnik

, et al. Pregnancy after bariatric surgery—A narrative literature review. Wideochir Inne Tech Maloinwazyjne, 2021; 16(1):30–37; doi: 10.5114/wiitm.2020.99281

Günakan

, Buluş

, Tohma

. Early pregnancy after bariatric surgery: A single-institute preliminary experience. Turk J Med Sci, 2020; 50(1):171–176; doi: 10.3906/sag-1909-139

Gidiri

, Greer

. Pregnancy after bariatric surgery: No problem?. Obstet Med, 2009; 2(1):11–16; doi: 10.1258/om.2008.080038.

Wilcox

, Liu

, Addy

, et al. A randomized controlled trial to prevent excessive gestational weight gain and promote postpartum weight loss in overweight and obese women: Health in pregnancy and postpartum (Hipp). Contemp Clin Trials, 2018; 66:51–63; doi: 10.1016/j.cct.2018.01.008.

Istfan

, Lipartia

, Anderson

, et al. Approach to the patient: Management of the post-bariatric surgery patient with weight regain. J Clin Endocrinol Metab, 2021; 106(1):251–263; doi: 10.1210/clinem/dgaa702.

10.

Bahadori

, Esfehani

, Bahrami

, et al. Identifying the predictors of short term weight loss failure after Roux-En-Y gastric bypass. Int J Clin Pract, 2022; 2022:2685292; doi: 10.1155/2022/2685292.

11.

Elnahas

, Jackson

, Hong

. Management of failed laparoscopic Roux-en-Y gastric bypass. Bariatr Surg Pract Patient Care, 2014; 9(1):36–40; doi: 10.1089/bari.2013.0012

12.

El Ansari

, Elhag

. Weight regain and insufficient weight loss after bariatric surgery: Definitions, prevalence, mechanisms, predictors, prevention and management strategies, and knowledge Gaps-a scoping review. Obes Surg, 2021; 31(4):1755–1766; doi: 10.1007/s11695-020-05160-5.

13.

American College of Obstetricians and Gynecologists. ACOG practice bulletin no. 105: Bariatric surgery and pregnancy. Obstet Gynecol, 2009; 113,(6):1405–1413.

14.

Courcoulas

, King

, Belle

, et al. Seven-year weight trajectories and health outcomes in the longitudinal assessment of bariatric surgery (LABS) study. JAMA Surg, 2018; 153(5):427–434; doi: 10.1001/jamasurg.2017.5025

15.

Harrod

, Elman

, Vesco

, et al. Associations of pregnancy after bariatric surgery with long-term weight trajectories and birth weight: LABS-2 study. Obesity (Silver Spring), 2020; 28(11):2209–2215; doi: 10.1002/oby.22944

16.

Brönnimann

, Jung

, Niclauss

, et al. The impact of pregnancy on outcomes after bariatric surgery. Obes Surg, 2020; 30(8):3001–3009; doi: 10.1007/s11695-020-04643-9.

17.

Rottenstreich

, Shufanieh

, Kleinstern

, et al. The long-term effect of pregnancy on weight loss after sleeve gastrectomy. Surg Obes Relat Dis, 2018; 14(10):1594–1599; doi: 10.1016/j.soard.2018.07.008

18.

Quyên Pham

, Pigeyre

, Caiazzo

, et al. Does pregnancy influence long-term results of bariatric surgery?. Surg Obes Relat Dis, 2015; 11(5):1134–1139; doi: 10.1016/j.soard.2015.03.015

19.

Froylich

, Corcelles

, Daigle

, et al. The effect of pregnancy before and/or after bariatric surgery on weight loss. Surg Obes Relat Dis, 2016; 12(3):596–599; doi: 10.1016/j.soard.2015.09.005

20.

Dao

, Kuhn

, Ehmer

, et al. Pregnancy outcomes after gastric-bypass surgery. Am J Surg, 2006; 192(6):762–766; doi: 10.1016/j.amjsurg.2006.08.041

21.

Balestrin

, Urbanetz

, Barbieri

. et al. Pregnancy after bariatric surgery: A comparative study of post-bariatric pregnant women versus non-bariatric obese pregnant women. Obes Surg, 2019; 29:3142–3148; doi: 10.1007/s11695-019-03961-x

22.

Alamri

, Abdeen

. Maternal nutritional status and pregnancy outcomes post-bariatric surgery. Obes Surg, 2022; 32:1325–1340; doi: 10.1007/s11695-021-05822-y