Altered glucose profiles and risk for hypoglycaemia during oral glucose tolerance testing in pregnancies after gastric bypass surgery

Investigating a New Way to Assess Metabolic Risk in Pregnant Females with Prior RYGB Surgery

BACKGROUND

Obesity in pregnancy is linked to adverse clinical outcomes such as gestational diabetes. Recently, a risk score calculated by different ceramide concentrations was recognized as a new way to investigate cardiovascular risk. The aim was to analyze if the ceramide risk score and cardiometabolic risk vary between normal-weight, obese, and females with prior Roux-en-Y bypass surgery (RYGB) during pregnancy.

METHODS

Three cohorts were investigated: first, 25 pregnant females with a history of RYGB; second, 19 with preconception BMI ≥ 35 kg/m2; and third, 19 normal-weight (preconception BMI < 25 kg/m2). Around the 24th to 28th weeks of gestation routine laboratory assessments, 3 h 75 g oral and intravenous glucose tolerance tests were carried out. The correlation of ceramide risk scores and ceramide ratios (Cer(d18:1/18:0)/Cer(d18:1/16:0)) with metabolic parameters was analyzed via Pearson correlation. The cohorts were compared via ANOVA and unpaired t-tests.

RESULTS

The RYGB cohort had lower ceramide risk scores and ratios compared to obese pregnant females (7.42 vs. 9.34, p = 0.025; 0.33 vs. 0.47, p < 0.001). Ceramide risk score and ratio were found to correlate negatively with insulin sensitivity (measured with the Matsuda (r = -0.376, p = 0.031; r = -0.455, p = 0.008) and calculated sensitivity index (r = -0.358, p = 0.044; r = -0.621, p < 0.001) in females without RYGB. The ceramide risk score correlated positively with body fat in RYGB females (r = 0.650, p = 0.012).

CONCLUSIONS

We found that females after RYGB have lower ceramide risk scores and ceramide ratios compared to obese pregnant females, possibly indicating lower metabolic risk.

Gestational Diabetes Risk and Low Birth Weight After Metabolic Bariatric Surgery: a Complex Interplay to be Balanced

INTRODUCTION

Metabolic bariatric surgery (MBS) is known to improve the obstetric outcomes of women with obesity and to prevent gestational diabetes (GD). To what extent does MBS decreases GD, without incurring at additional risks is a matter of concern.

METHODS

A retrospective case-control study to compare the pregnancy outcomes of women previously submitted to MBS to those of age and preconception body mass index (PC BMI) matched non-operated controls.

RESULTS

Pregnancies of women after MBS (n = 79) and matched controls (n = 79) were included. GD was significantly less frequent after MBS (7.6% vs. 19%; p = 0.03). Fasting blood glucose (76.90 ± 0.77 vs 80.37 ± 1.15 mg/dl, p < 0.05; 70.08 ± 1.34 vs. 76.35 ± 0.95 mg/dl; p < 0.05, first and second trimesters respectively) and birth weight (2953.67 ± 489.51 g vs. 3229.11 ± 476.21 g; p < 0.01) were significantly lower after MBS when compared to controls. The occurrence of small-for-gestational-age (SGA) was more frequent after MBS (22.8% vs. 6.3%; p < 0.01), but no longer significant after controlling for smoking habits (15.5% vs. 6%, p = 0.14). There were no significant differences in gestational weight gain, prematurity rate nor mode of delivery between groups.

CONCLUSION

MBS was associated with a lower prevalence of GD than observed in non-operated women with the same age and BMI. After controlling for smoking, this occurred at the expense of a lower birth weight. Our data reinforces the hypothesis that MBS has body weight independent effects on glucose kinetics during pregnancy with distinctive impacts for mother and offspring, which need to be balanced.

Pregnancy After Bariatric Surgery-Experience from a Tertiary Center

INTRODUCTION

It is estimated that most people undergoing bariatric surgery are women of reproductive age; nonetheless, its effects on pregnancy outcomes are not yet fully understood.

METHODS

Retrospective observational study, conducted in a tertiary center in Portugal, included participants in two groups: (1) pregnant women with a history of bariatric surgery (n = 89) and (2) pregnant women with a BMI ≥ 35 kg/m2, without previous bariatric surgery (n = 176). Data was collected from the medical files. Multivariate analysis was conducted to adjust for confounders.

RESULTS

Pregnancy after bariatric surgery was associated with lower risk of gestational diabetes (15.7% vs. 30.1%, p = 0.002) and cesarean delivery (20.7% vs. 33.5%, p = 0.007), and a higher gestational weight gain (10.58 ± 9.95 vs. 7.33 ± 6.00 kg, p < 0.001). Participants in the bariatric surgery who experienced a gestational weight gain ≤ 10.0 kg had a higher risk of preterm delivery (16.7% vs. 2.5%, p = 0.031). No significant differences were found regarding hypertensive diseases of pregnancy between groups (4.5% vs 11.4%, p = 0.147). Pregnancy after bariatric surgery was associated with lower neonate weight percentile (34.24 ± 21.09 vs. 48.77 ± 27.94, p < 0.001), higher risk of fetal growth restriction (5.6% vs. 0.6%, p = 0.018), and lower risk of fetal macrosomia (0.0% vs. 7.5%, p = 0.005). There were no significant differences in the risk of SGA (12.5% vs. 7.0%, p = 0.127) or LGA neonates (2.3% vs. 6.4%, p = 0.069).

CONCLUSION

Pregnancy after bariatric surgery is associated with both risks and benefits, which should be considered by healthcare providers. Pregnancy after bariatric surgery requires individualized care, to ensure adequate gestational weight and avoid micronutrient deficiencies.

Comment: pregnancy after bariatric surgery - achievements and open questions

Bariatric surgery confers potential advantages for obese patients, but also risks for pregnancy. Perinatal outcomes may be varying between surgical procedures. This topic was recently addressed by a systematic review in BMC Pregnancy and Childbirth. This commentary will discuss the scientific background and implications for future research.

Roux-en-Y Gastric Bypass Increases Glycemic Excursions During Pregnancy and Postpartum: A Prospective Cohort Study

OBJECTIVE

Roux-en-Y gastric bypass (RYGB) and pregnancy markedly alter glucose metabolism, but evidence on glucose metabolism in pregnancy after RYGB is limited. Thus, the aims of the Bariatric Surgery and Consequences for Mother and Baby in Pregnancy study were to investigate interstitial glucose (IG) profiles during pregnancy, risk factors associated with hypoglycemia, and the association between fetal growth and hypoglycemia in pregnant women previously treated with RYGB, compared with control participants.

RESEARCH DESIGN AND METHODS

Twenty-three pregnant women with RYGB and 23 BMI- and parity-matched pregnant women (control group) were prospectively studied with continuous glucose monitoring in their first, second, and third trimesters, and 4 weeks postpartum. Time in range (TIR) was defined as time with an IG level of 3.5-7.8 mmol/L.

RESULTS

Women with RYGB were 4 years (interquartile range [IQR] 0-7) older than control participants. Pregnancies occurred 30 months (IQR 15-98) after RYGB, which induced a reduction in BMI from 45 kg/m2 (IQR 42-54) presurgery to 32 kg/m2 (IQR 27-39) prepregnancy. Women with RYGB spent decreased TIR (87.3-89.5% vs. 93.3-96.1%; P < 0.01) owing to an approximately twofold increased time above range and increased time below range (TBR) throughout pregnancy and postpartum compared with control participants. Women with increased TBR had a longer surgery-to-conception interval, lower nadir weight, and greater weight loss after RYGB. Finally, women giving birth to small-for-gestational age neonates experienced slightly increased TBR.

CONCLUSIONS

Women with RYGB were more exposed to hypoglycemia and hyperglycemia during pregnancy compared with control participants. Further research should investigate whether hypoglycemia during pregnancy in women with RYGB is associated with decreased fetal growth.

Risk factors of lower birth weight, small-for-gestational-age infants, and preterm birth in pregnancies following bariatric surgery: a scoping review

PURPOSE

Bariatric surgery increases the risk of lower birth weight, small-for-gestational-age (SGA) infants, and preterm birth in a subsequent pregnancy. However, the factors that contribute to these adverse birth outcomes are unclear. This review aimed to collate available information about risk factors of lower birth weight, SGA, and preterm birth following bariatric surgery.

METHODS

A literature search was conducted using five databases (PubMed, PsycINFO, EMBASE, Web of Science, and Cochrane Library) to obtain relevant studies.

RESULTS

A total number of 85 studies were included. Studies generally excluded surgery-to-conception interval, pregnancy complications, cigarette use, and maternal age as influencing factors of birth weight, SGA, or preterm birth. In contrast, most studies found that malabsorptive procedures, lower gestational weight gain, lower glucose levels, abdominal pain, and insufficient prenatal care were associated with an elevated risk of adverse birth outcomes. Findings were mixed regarding the effects of surgery-to-conception weight loss, pre-pregnancy body mass index, micronutrient deficiency, and lipid levels on birth outcomes. The examination of maternal microbiome profiles, placental function, alcohol use, and exercise was limited to one study; therefore, no conclusions could be made.

CONCLUSION

This review identified factors that appear to be associated (e.g., surgery type) or not associated (e.g., surgery-to-conception interval) with birth outcomes following bariatric surgery. The mixed findings and the limited number of studies on several variables (e.g., micronutrients, exercise) highlight the need for further investigation. Additionally, future studies may benefit from exploring interactions among risk factors and expanding to assess additional exposures such as maternal mental health.

Hypoglycemia in Pregnancies Following Gastric Bypass-a Systematic Review and Meta-analysis

The aims of this systematic review were to identify the prevalence of hypoglycemia among pregnant women treated with gastric bypass, and risk factors of hypoglycemic events in pregnancy. We searched MEDLINE, EMBASE, Cochrane, and Scopus databases from inception to April 6, 2021. Six studies investigating glucose metabolism in pregnancy following gastric bypass were included (n = 330). As assessed by the oral glucose tolerance test and continuous glucose monitoring, 57.6% (95% CI [40.1, 75.1]) of women with gastric bypass were exposed to hypoglycemia during pregnancy. No studies performed the mixed meal test, and no studies reported on risk factors associated with hypoglycemia. Further studies are required to determine the magnitude of hypoglycemia in these women's everyday-life using continuous glucose monitoring and mixed meal test.

An Update on Screening Strategies for Gestational Diabetes Mellitus: A Narrative Review

Gestational diabetes mellitus (GDM) is a frequent medical complication during pregnancy. Screening and diagnostic practices for GDM are inconsistent across the world. This narrative review includes data from 87 observational studies and randomized controlled trials (RCTs), and aims to give an overview of the current evidence on screening strategies and diagnostic criteria for GDM. Screening in early pregnancy remains controversial and studies show conflicting results on the benefit of screening and treatment of GDM in early pregnancy. Implementing the one-step "International Association of Diabetes and Pregnancy Study Groups" (IADPSG) screening strategy at 24-28 weeks often leads to a substantial increase in the prevalence of GDM, without conclusive evidence regarding the benefits on pregnancy outcomes compared to a two-step screening strategy with a glucose challenge test (GCT). In addition, RCTs are needed to investigate the impact of treatment of GDM diagnosed with IADPSG criteria on long-term maternal and childhood outcomes. Selective screening using a risk-factor-based approach could be helpful in simplifying the screening algorithm but carries the risk of missing significant proportions of GDM cases. A two-step screening method with a 50g GCT and subsequently a 75g oral glucose tolerance test (OGTT) with IADPSG could be an alternative to reduce the need for an OGTT. However, to have an acceptable sensitivity to screen for GDM with the IADPSG criteria, the threshold of the GCT should be lowered from 7.8 to 7.2 mmol/L. A pragmatic approach to screen for GDM can be implemented during the COVID-19 pandemic, using fasting plasma glucose (FPG), HbA1c or even random plasma glucose (RPG) to reduce the number of OGTTs needed. However, usual guidelines and care should be resumed as soon as the COVID pandemic is controlled.

Glucose Abnormalities and Inappropriate Weight Gain Predict Negative Pregnancy Outcomes After Gastric Bypass Surgery

PURPOSE

Pregnancy after gastric bypass (RYGB) surgery remains at high risk for gestational diabetes mellitus, prematurity, and small for gestational age infants (SGA). Our objective was to describe the interstitial glucose (IG) profiles and weight changes during such pregnancies, and the association of these factors with adverse pregnancy outcomes.

MATERIAL AND METHODS

One hundred twenty two pregnancies were analyzed in a monocentric retrospective study. IG profiles were evaluated by continuous glucose monitoring for 4 days. Maternal (hypertension, hospitalizations, and caesarean section) and neonatal outcomes (prematurity, weight for gestational age, hospitalizations, and malformations) were recorded. A logistic stepwise regression model assessed the influence of weight gain and impaired IG on pregnancy outcomes.

RESULTS

Pregnancies occurred 33 (SD 21 months) after surgery. 73% of the women had IG abnormalities (55% with an increased % of time >140 mg/dl and 69% with an increased % of time <60 mg/dl). Five (4%) children were large for gestational age (LGA), 24 (20%) were SGA and 16 (13%) were born prematurely. There were 3 malformations but no stillbirth. LGA was associated with a high % of time >140 mg/dl and an excessive maternal weight gain. Prematurity was associated with a high % of time <60 mg/dl and an insufficient maternal weight gain. In the multivariate analysis, inappropriate weight gain explained LGA and prematurity independently. SGA was associated with a shorter % of time <60 mg/dl.

CONCLUSION

The relationship between IG abnormalities and/or maternal weight gain and neonatal outcomes in pregnancies after RYGB, suggests a careful monitoring of these parameters.

Hyperglycemia at 1h-OGTT in Pregnancy: A Reliable Predictor of Metabolic Outcomes?

Gestational diabetes mellitus (GDM) is associated with a high risk of developing type 2 diabetes (T2DM) and cardiovascular disease (CVD). Identifying among GDM women those who are at high risk may help prevent T2DM and, possibly CVD. Several studies have shown that in women with GDM, hyperglycemia at 1 h during an oral glucose tolerance test (OGTT) (1-h PG) is not only associated with an increase in adverse maternal and perinatal outcomes but is also an independent predictor of T2DM. Interestingly, also in pregnant women who did not meet the criteria for a GDM diagnosis, 1-h PG was an independent predictor of postpartum impaired insulin sensitivity and beta-cell dysfunction. Moreover, maternal 1- and 2-h PG levels have been found to be independently associated with insulin resistance and impaired insulin secretion also during childhood. There is evidence that hyperglycemia at 1h PG during pregnancy may identify women at high risk of future CVD, due to its association with an unfavorable CV risk profile, inflammation, arterial stiffness and endothelial dysfunction. Overall, hyperglycemia at 1h during an OGTT in pregnancy may be a valuable prediction tool for identifying women at a high risk of future T2DM, who may then benefit from therapeutic strategies aimed at preventing cardiovascular outcomes.

The 2019 Flemish consensus on screening for overt diabetes in early pregnancy and screening for gestational diabetes mellitus

Screening for gestational diabetes mellitus (GDM) is important to improve pregnancy outcomes and to prevent type 2 diabetes after pregnancy. The 'International Association of Diabetes and Pregnancy Study Groups' (IADPSG) recommends a universal one-step approach with the 75 g oral glucose tolerance test (OGTT) for screening of GDM. The IADPSG recommendation remains controversial due to the important increase in GDM prevalence and increased workload. After review of the latest evidence and based on data from the 'Belgian Diabetes in Pregnancy' study, members of the Diabetes Liga, the Flemish associations of general physicians (Domus Medica), obstetricians (VVOG), midwives (VVOB), diabetes nurse educators (BVVDV) and clinical chemists (RBSLM) have reached a new consensus on screening for GDM in Flanders. This new consensus recommends universal screening for overt diabetes when planning pregnancy or at the latest at first prenatal contact, preferably by measuring the fasting plasma glucose by using the same diagnostic criteria as in the non-pregnant state. In women with impaired fasting glycaemia, but also in normoglycemic obese women and women with a previous history of GDM, lifestyle counselling is advised with screening for GDM with a 75 g OGTT at 24 weeks. In all other women, we recommend a two-step screening strategy with a 50 g glucose challenge test (GCT) at 24 weeks followed by a 75 g OGTT when the glucose level 1 hour after the GCT ≥130 mg/dl. Diagnosis of GDM is made using the IADPSG criteria for GDM. Postpartum screening for subsequent glucose abnormalities should be advocated and organized for every woman with GDM.

Glucose Homeostasis, Fetal Growth and Gestational Diabetes Mellitus in Pregnancy after Bariatric Surgery: A Scoping Review

Background: Pregnancies in women with a history of bariatric surgery are becoming increasingly prevalent. Surgically induced metabolic changes benefit mother and child, but can also lead to some adverse pregnancy outcomes. Knowledge about glucose homeostasis in these pregnancies could elucidate some of the mechanisms behind these outcomes. This review focusses on glucose homeostasis and birth weight. Methods: We considered papers dealing with glucose homeostasis, gestational diabetes mellitus (GDM) and/or small-for-gestational age infants (SGA) in pregnancies with a history of sleeve gastrectomy (SG) or Roux-en-y gastric bypass (RYGB). Results: Since an OGTT is unreliable to diagnose GDM in a pregnancy after bariatric surgery, the true incidence of GDM is unknown. Alternative screening strategies are needed. Furthermore, these pregnancies are marked by frequent hypoglycemic events as well as wide and rapid glycemic excursions, an issue that is very likely underreported. There is a lack of uniformity in reporting key outcomes and a large variation in study design and control population. Conclusion: Alteration of glucose homeostasis in a pregnancy after bariatric surgery should be further studied using unequivocal definition of key concepts. Glycemic control may prove to be a modifiable risk factor for adverse pregnancy outcomes such as the delivery of an SGA baby.

Clinical Practice Guidelines for Childbearing Female Candidates for Bariatric Surgery, Pregnancy, and Post-partum Management After Bariatric Surgery

Emerging evidence suggests that bariatric surgery improves pregnancy outcomes of women with obesity by reducing the rates of gestational diabetes, pregnancy-induced hypertension, and macrosomia. However, it is associated with an increased risk of a small-for-gestational-age fetus and prematurity. Based on the work of a multidisciplinary task force, we propose clinical practice recommendations for pregnancy management following bariatric surgery. They are derived from a comprehensive review of the literature, existing guidelines, and expert opinion covering the preferred type of surgery for women of childbearing age, timing between surgery and pregnancy, contraception, systematic nutritional support and management of nutritional deficiencies, screening and management of gestational diabetes, weight gain during pregnancy, gastric banding management, surgical emergencies, obstetrical management, and specific care in the postpartum period and for newborns.

Micronutrient management following bariatric surgery: the role of the dietitian in the postoperative period

Bariatric surgery is increasingly being utilized to manage obesity and obesity related comorbidities, but may lead to the development of micronutrient deficiencies postoperatively. The anatomical, physiological, nutritional and behavioral reasons for micronutrient vulnerabilities are reviewed, along with recommendations for routine monitoring and replacement following surgery. The role the dietitian and their contribution in the postoperative identification, prevention and management of micronutrient vulnerabilities in bariatric patients is described. Specific considerations such as the nutritional and dietetic management of pregnant and lactating women post-bariatric surgery is also discussed.

Fetal growth and fetoplacental circulation in pregnancies following bariatric surgery: a prospective study

OBJECTIVE

To investigate the intrauterine fetal growth pattern and fetoplacental circulation in pregnancies following bariatric surgery.

DESIGN

Prospective study.

SETTING

Maternity Unit, UK.

POPULATION

One hundred and sixty-two pregnant women; 54 with previous bariatric surgery and 108 with no surgery but similar booking body mass index.

METHODS

Participants were seen at 11-14, 20-24, 30-33 and 35-37 weeks of gestation and an oral glucose tolerance test (OGTT) was performed at 27-30 weeks. Fetal head and abdominal circumference (AC), femur length (FL), estimated fetal weight (EFW) and fetoplacental Dopplers were measured at three time-points in pregnancy. Birthweight (BW) was recorded. Variables were modelled after adjustment for maternal/pregnancy characteristics. Model estimates are reported as posterior means and quantile-based 90% credible intervals (CrI).

MAIN OUTCOME MEASURES

Fetal biometry, fetoplacental Doppler, BW.

RESULTS

Compared with the no surgery group, the post-bariatric surgery group had lower EFW during gestation (up to -120 g; [-189 g, -51 g] lighter) at 35-37 weeks, with smaller AC and FL. Similarly, infants of mothers with previous bariatric surgery had lower average BW [-202 g [-330 g, -72 g] lighter). Overall, there was no difference in the fetoplacental Doppler indices between groups but maternal glucose levels at OGTT were positively correlated with third-trimester EFW and BW.

CONCLUSIONS

Fetuses of women with previous bariatric surgery are smaller during pregnancy and at birth, compared with those of women without such surgery, and this may be related to the lower maternal glucose levels seen in the former population. The fetoplacental circulation appears not to be altered by maternal weight loss surgery.

TWEETABLE ABSTRACT

Offspring of post-bariatric women are smaller during pregnancy and at birth but this is not due to placental insufficiency.

Maternal, neonatal insulin resistance and neonatal anthropometrics in pregnancies following bariatric surgery

OBJECTIVE

An increasing number of women present pregnant having undergone bariatric surgery, a popular treatment for sustainable weight loss. The aim of the study was to investigate the effect, if any, of bariatric surgery on maternal and neonatal insulin resistance (IR) and neonatal body fat composition.

METHODS

Maternal IR, at 28 weeks of gestation during 2-hour 75 g oral glucose tolerance test (OGTT), neonatal IR, from umbilical cord venous blood, and neonatal birthweight and body fat composition (calculated by measuring skin folds) at birth were evaluated in 41 post-bariatric and 82 pregnant women with similar early pregnancy body mass index but no history of such surgery. Insulin resistance was assessed using the homeostasis model assessment of IR (HOMA-IR).

RESULTS

In the post-bariatric surgery group, compared to the no surgery group, maternal HOMA-IR (1.15 [1.04-2.07] vs 2.20 [1.53-3.38]; p < 0.01), neonatal birthweight (p < 0.01) and body fat (p < 0.01) were significantly lower whereas neonatal cord HOMA-IR was similar (1.29 [0.65-2.39] vs 1.19 [0.46-1.93]; p = 0.49). In the no surgery group, there was a positive correlation between maternal and neonatal HOMA-IR (p = 0.03) and between neonatal HOMA-IR and body fat (p < 0.01). However, no such significant correlations were detected in the post-bariatric surgery group.

CONCLUSION

Pregnancy following bariatric surgery is associated with a reduction in maternal IR and altered neonatal body composition with significantly lower birthweight and adiposity but no improvement in cord IR.

Pregnancy after bariatric surgery and adverse perinatal outcomes: A systematic review and meta-analysis

BACKGROUND

Women who undergo bariatric surgery prior to pregnancy are less likely to experience comorbidities associated with obesity such as gestational diabetes and hypertension. However, bariatric surgery, particularly malabsorptive procedures, can make patients susceptible to deficiencies in nutrients that are essential for healthy fetal development. The objective of this systematic review and meta-analysis is to investigate the association between pregnancy after bariatric surgery and adverse perinatal outcomes.

METHODS AND FINDINGS

Searches were conducted in Medline, Embase, PsycINFO, CINAHL, Scopus, and Google Scholar from inception to June 2019, supplemented by hand-searching reference lists, citations, and journals. Observational studies comparing perinatal outcomes post-bariatric surgery to pregnancies without prior bariatric surgery were included. Outcomes of interest were perinatal mortality, congenital anomalies, preterm birth, postterm birth, small and large for gestational age (SGA/LGA), and neonatal intensive care unit (NICU) admission. Pooled effect sizes were calculated using random-effects meta-analysis. Where data were available, results were subgrouped by type of bariatric surgery. We included 33 studies with 14,880 pregnancies post-bariatric surgery and 3,979,978 controls. Odds ratios (ORs) were increased after bariatric surgery (all types combined) for perinatal mortality (1.38, 95% confidence interval [CI] 1.03-1.85, p = 0.031), congenital anomalies (1.29, 95% CI 1.04-1.59, p = 0.019), preterm birth (1.57, 95% CI 1.38-1.79, p < 0.001), and NICU admission (1.41, 95% CI 1.25-1.59, p < 0.001). Postterm birth decreased after bariatric surgery (OR 0.46, 95% CI 0.35-0.60, p < 0.001). ORs for SGA increased (2.72, 95% CI 2.32-3.20, p < 0.001) and LGA decreased (0.24, 95% CI 0.14-0.41, p < 0.001) after gastric bypass but not after gastric banding. Babies born after bariatric surgery (all types combined) weighed over 200 g less than those born to mothers without prior bariatric surgery (weighted mean difference -242.42 g, 95% CI -307.43 to -177.40 g, p < 0.001). There was low heterogeneity for all outcomes (I2 < 40%) except LGA. Limitations of our study are that as a meta-analysis of existing studies, the results are limited by the quality of the included studies and available data, unmeasured confounders, and the small number of studies for some outcomes.

CONCLUSIONS

In our systematic review of observational studies, we found that bariatric surgery, especially gastric bypass, prior to pregnancy was associated with increased risk of some adverse perinatal outcomes. This suggests that women who have undergone bariatric surgery may benefit from specific preconception and pregnancy nutritional support and increased monitoring of fetal growth and development. Future studies should explore whether restrictive surgery results in better perinatal outcomes, compared to malabsorptive surgery, without compromising maternal outcomes. If so, these may be the preferred surgery for women of reproductive age.

TRIAL REGISTRATION

PROSPERO CRD42017051537.

Glucagon-like peptide 1 (GLP-1) drives postprandial hyperinsulinemic hypoglycemia in pregnant women with a history of Roux-en-Y gastric bypass operation

BACKGROUND

The influential role of incretin hormones on glucose metabolism in patients with a history of Roux-en-Y gastric bypass (RYGB) has been investigated thoroughly, but there has been little examination of the effect of incretins and ectopic lipids on altered glucose profiles, especially severe hypoglycemia in pregnant women with RYGB.

METHODS

In this prospective clinical study, an oral glucose tolerance test (OGTT), an intravenous glucose tolerance test (IVGTT), and continuous glucose monitoring (CGM) were conducted in 25 women with RYGB during pregnancy, 19 of normal weight (NW) and 19 with obesity (OB) between the 24th and the 28th weeks of pregnancy, and 3 to 6 months post-partum. Post-partum, the ectopic lipid content in the liver, heart, and skeletal muscle was analyzed using ¹H-magnetic resonance spectroscopy (¹H-MRS).

RESULTS

RYGB patients presented with major fluctuations in glucose profiles, including a high occurrence of postprandial hyperglycemic spikes and hypoglycemic events during the day, as well as a high risk of hypoglycemic periods during the night (2.9 ± 1.1% vs. 0.1 ± 0.2% in the OB and vs. 0.8 ± 0.6% in the NW groups, p < 0.001). During the extended OGTT, RYGB patients presented with exaggerated expression of GLP-1, which was the main driver of the exaggerated risk of postprandial hypoglycemia in a time-lagged correlation analysis. Basal and dynamic GLP-1 levels were not related to insulin sensitivity, insulin secretion, or beta cell function and did not differ between pregnant women with and without GDM. A lower amount of liver fat (2.34 ± 5.22% vs.5.68 ± 4.42%, p = 0.015), which was positively related to insulin resistance (homeostasis model assessment of insulin resistance, HOMA-IR: rho = 0.61, p = 0.002) and beta-cell function (insulinogenic index: rho = 0.65, p = 0.001), was observed in the RYGB group after delivery in comparison to the OB group.

CONCLUSION

GLP-1 is mainly involved in the regulation of postprandial glucose metabolism and therefore especially in the development of postprandial hypoglycemia in pregnant RYGB patients, who are characterized by major alterations in glucose profiles, and thus in long-term regulation, multiple organ-related mechanisms, such as the lipid content in the liver, must be involved.

Pregnancy after bariatric surgery: a narrative literature review and discussion of impact on pregnancy management and outcome

Bariatric surgery (BS) is regarded to be the most effective treatment of obesity with long lasting beneficial effects including weight loss and improvement of metabolic disorders. A considerable number of women undergoing BS are at childbearing age.Although the surgery mediated weight loss has a positive effect on pregnancy outcome, the procedures might be associated with adverse outcomes as well, for example micronutrient deficiencies, iron or B12 deficiency anemia, dumping syndrome, surgical complications such as internal hernias, and small for gestational age (SGA) offspring, possibly due to maternal undernutrition. Also, there is no international consensus concerning the ideal time to conception after BS. Hence, the present narrative review intents to summarize the available literature concerning the most common challenges which arise before and during pregnancy after BS, such as fertility related considerations, vitamin and nutritional deficiencies and their adequate compensation through supplementation, altered glucose metabolism and its implications for gestational diabetes screening, the symptoms and treatment of dumping syndrome, surgical complications and the impact of BS on pregnancy outcome. The impact of different bariatric procedures on pregnancy and fetal outcome will also be discussed, as well as general considerations concerning the monitoring and management of pregnancies after BS.Whereas BS leads to the mitigation of many obesity-related pregnancy complications, such as gestational diabetes mellitus (GDM), pregnancy induced hypertension and fetal macrosomia; those procedures pose new risks which might lead to adverse outcomes for mothers and offspring, for example nutritional deficiencies, anemia, altered maternal glucose metabolism and small for gestational age children.

Fertility, Pregnancy and Lactation After Bariatric Surgery - a Consensus Statement from the OEGGG

Bariatric surgery is recommended when other weight loss interventions, such as lifestyle modification or medications, have failed. A considerable number of women undergoing bariatric surgery are of childbearing age; hence, it is necessary to be aware of the effects of bariatric surgery on pregnancy for managing these patients. Although bariatric surgery is associated with positive effects on cardiovascular and metabolic parameters, side effects such as anaemia, the risk of developing internal hernia, altered glucose metabolism and the risk of small for gestational age offspring have to be considered. Pregnant women with a history of gastric bypass should not undergo the oral glucose tolerance test (OGTT) due to the high risk of hypoglycaemia. There are no contraindications for vaginal delivery and breastfeeding. This paper has been published as a consensus statement by the Austrian Society of Gynaecology and Obstetrics (OEGGG).

Screening and Management of Gestational Diabetes Mellitus after Bariatric Surgery

Gestational diabetes mellitus (GDM) is a frequent medical complication during pregnancy. This is partly due to the increasing prevalence of obesity in women of childbearing age. Since bariatric surgery is currently the most successful way to achieve maintained weight loss, increasing numbers of obese women of childbearing age receive bariatric surgery. Bariatric surgery performed before pregnancy significantly reduces the risk to develop GDM but the risk is generally still higher compared to normal weight pregnant women. Women after bariatric surgery therefore still require screening for GDM. However, screening for GDM is challenging in pregnant women after bariatric surgery. The standard screening tests such as an oral glucose tolerance test are often not well tolerated and wide variations in glucose excursions make the diagnosis difficult. Capillary blood glucose measurements may currently be the most acceptable alternative for screening in pregnancy after bariatric surgery. In addition, pregnant women after bariatric surgery have an increased risk for small neonates and need careful nutritional and foetal monitoring. In this review, we address the risk to develop GDM after bariatric surgery, the challenges to screen for GDM and the management of women with GDM after bariatric surgery.

Diagnosis and follow-up of type 2 diabetes in women with PCOS: a role for OGTT?

Polycystic ovary syndrome (PCOS) is common in premenopausal women. The majority of women with PCOS have insulin resistance and the risk of type 2 diabetes mellitus (T2D) is higher in women with PCOS compared to controls. In non-pregnant women with PCOS, glycemic status may be assessed by oral glucose tolerance test (OGTT), fasting plasma glucose (FPG) or HbA1c. OGTT has been reckoned gold standard test for diagnosing T2D, but OGTT is rarely used for diagnostic purpose in other non-pregnant individuals at risk of T2D, apart from PCOS. OGTT has questionable reproducibility, and high sensitivity of the 2-h glucose value is at the expense of relatively low specificity, especially regarding impaired glucose tolerance (IGT). Furthermore, lean women with PCOS are rarely diagnosed with T2D and only few percent of normal-weight women have prediabetes. Glycemic status is necessary at diagnosis and during follow-up of PCOS, especially in women with high risk of T2D (obesity, previous gestational diabetes (GDM)). We suggest that OGTT should be used in the same situations in PCOS as in other patient groups at risk of T2D. OGTT is indicated for diagnosing GDM; however, OGTT during pregnancy may not be indicated in lean women with PCOS without other risk factors for GDM.

Management of Pregnant Women after Bariatric Surgery

The prevalence of obesity is growing worldwide, and strategies to overcome this epidemic need to be developed urgently. Bariatric surgery is a very effective treatment option to reduce excess weight and often performed in women of reproductive age. Weight loss influences fertility positively and can resolve hormonal imbalance. So far, guidelines suggest conceiving after losing maximum weight and thus recommend conception at least 12-24 months after surgery. As limited data of these suggestions exist, further evidence is urgently needed as well for weight gain in pregnancy. Oral glucose tolerance tests for the diagnosis of gestational diabetes mellitus (GDM) should not be performed after bariatric procedures due to potential hypoglycaemic adverse events and high variability of glucose levels after glucose load. This challenges the utility of the usual diagnostic criteria for GDM in accurate prediction of complications. Furthermore, recommendations on essential nutrient supplementation in pregnancy and lactation in women after bariatric surgery are scarce. In addition, nutritional deficiencies or daily intake recommendations in pregnant women after bariatric surgery are not well investigated. This review summarizes current evidence, proposes clinical recommendations in pregnant women after bariatric surgery, and highlights areas of lack of evidence and the resulting urgent need for more clinical investigations.

Maternal and neonatal outcomes after bariatric surgery; a systematic review and meta-analysis: do the benefits outweigh the risks?

OBJECTIVE DATA

Obesity during pregnancy is associated with a number of adverse obstetric outcomes that include gestational diabetes mellitus, macrosomia, and preeclampsia. Increasing evidence shows that bariatric surgery may decrease the risk of these outcomes. Our aim was to evaluate the benefits and risks of bariatric surgery in obese women according to obstetric outcomes.

STUDY

We performed a systematic literature search using MEDLINE, Embase, Cochrane, Web of Science, and PubMed from inception up to December 12, 2016. Studies were included if they evaluated patients who underwent bariatric surgery, reported subsequent pregnancy outcomes, and compared these outcomes with a control group.

STUDY APPRAISAL AND SYNTHESIS METHODS

Two reviewers extracted study outcomes independently, and risk of bias was assessed with the use of the Newcastle-Ottawa Quality Assessment Scale. Pooled odds ratios for each outcome were estimated with the Dersimonian and Laird random effects model.

RESULTS

After a review of 2616 abstracts, 20 cohort studies and approximately 2.8 million subjects (8364 of whom had bariatric surgery) were included in the metaanalysis. In our primary analysis, patients who underwent bariatric surgery showed reduced rates of gestational diabetes mellitus (odds ratio, 0.20; 95% confidence interval, 0.11-0.37, number needed to benefit, 5), large-for-gestational-age infants (odds ratio, 0.31; 95% confidence interval, 0.17-0.59; number needed to benefit, 6), gestational hypertension (odds ratio, 0.38; 95% confidence interval, 0.19-0.76; number needed to benefit, 11), all hypertensive disorders (odds ratio, 0.38; 95% confidence interval, 0.27-0.53; number needed to benefit, 8), postpartum hemorrhage (odds ratio, 0.32; 95% confidence interval, 0.08-1.37; number needed to benefit, 21), and caesarean delivery rates (odds ratio, 0.50; 95% confidence interval, 0.38-0.67; number needed to benefit, 9); however, group of patients showed an increase in small-for-gestational-age infants (odds ratio, 2.16; 95% confidence interval, 1.34-3.48; number needed to harm, 21), intrauterine growth restriction (odds ratio, 2.16; 95% confidence interval, 1.34-3.48; number needed to harm, 66), and preterm deliveries (odds ratio, 1.35; 95% confidence interval, 1.02-1.79; number needed to harm, 35) when compared with control subjects who were matched for presurgery body mass index. There were no differences in rates of preeclampsia, neonatal intensive care unit admissions, stillbirths, malformations, and neonatal death. Malabsorptive surgeries resulted in a greater increase in small-for-gestational-age infants (P=.0466) and a greater decrease in large-for-gestational-age infants (P=<.0001) compared with restrictive surgeries. There were no differences in outcomes when we used administrative databases vs clinical charts.

CONCLUSION

Although bariatric surgery is associated with a reduction in the risk of several adverse obstetric outcomes, there is a potential for an increased risk of other important outcomes that should be considered when bariatric surgery is discussed with reproductive-age women.

Rodent vertical sleeve gastrectomy alters maternal immune health and fetoplacental development

Bariatric surgery is increasingly employed to improve fertility and reduce obesity-related co-morbidities in obese women. Surgical weight loss not only improves the chance of conception but reduces the risk of pregnancy complications including pre-eclampsia, gestational diabetes, and macrosomia. However, bariatric procedures increase the incidence of intrauterine growth restriction (IUGR), fetal demise, thromboembolism, and other gestational disorders. Using our rodent model of vertical sleeve gastrectomy (VSG), we tested the hypothesis that VSG in diet-induced, obese dams would cause immune and placental structural abnormalities that may be responsible for fetal demise during pregnancy. VSG dams studied on gestational day (G) 19 had reduced circulating T-cell (CD3+ and CD8+) populations compared with lean or obese controls. Further, local interleukin (IL) 1β and IL 1 receptor antagonist (il1rn) cmRNA were increased in placenta of VSG dams. Placental barrier function was also affected, with increased transplacental permeability to small molecules, increased matrix metalloproteinase 9 expression, and increased apoptosis in VSG. Furthermore, we identified increased placental mTOR signaling that may contribute to preserving the body weight of the fetuses during gestation. These changes occurred in the absence of a macronutrient deficit or gestational hypertension in the VSG dams. In summary, previous VSG in dams may contribute to fetal demise by affecting maternal immune system activity and compromise placental integrity.

Pregnancy after bariatric surgery: Maternal and fetal outcomes of 39 pregnancies and a literature review

AIM

We aimed to evaluate the impact of bariatric surgery (BS) on maternal and fetal outcomes.

METHODS

A retrospective, descriptive, observational study of 39 pregnant women who underwent BS in our institution between 2010 and 2014 was carried out. A sample of women who became pregnant after BS was evaluated, based on data concerning pregnancy, childbirth, and newborns.

RESULTS

Of the 1182 patients who underwent BS at our institution during the study period, 1016 (85.9%) were women. Thirty-nine of these women (with an average age of 31 ± 4.8 years) became pregnant (one twin pregnancy) and 29 of the 39 had undergone a gastric bypass. The mean time interval between BS and pregnancy was 16.6 ± 4.8 months; however, 16 (41%) women became pregnant less than a year after BS. The pre-BS body mass index (BMI) of the 39 women was 44.5 ± 6.2 kg/m² . The women had a mean BMI of 30.2 ± 3.8 kg/m² when they got pregnant and they gained 13.2 ± 7.3 kg during pregnancy. Iron deficiency was observed in 18 (46.1%) women, 16 (45.7%) had vitamin B12 deficiency, 12 (66.8%) had zinc deficiency, and 20 (60.6%) had vitamin D deficiency. Three women developed gestational diabetes mellitus. Premature rupture of membranes occurred in two pregnancies, preterm delivery in five, and there was one spontaneous abortion. Cesarean section was performed in seven cases. The average newborn weight was 3002 ± 587 g, five were small for gestational age, and one had macrosomia. Three infants had to be admitted to an intensive care unit.

CONCLUSION

Although pregnancy after BS is safe and well tolerated, close monitoring by a multidisciplinary team is required to evaluate complications resulting from BS, especially a deficit of micronutrients.

Hypoglycemia during oral glucose tolerance test among post-bariatric surgery pregnant patients: incidence and perinatal significance

BACKGROUND

While hypoglycemia during an oral glucose tolerance test (OGTT) has been shown to occur in a considerable portion of nonpregnant post-bariatric surgery (BS) patients, its incidence among pregnant post-BS patients evaluated for gestational diabetes has only been sparsely studied.

OBJECTIVES

We investigated OGTT results and pregnancy outcomes in pregnant women who underwent 3 types of bariatric procedures before pregnancy.

SETTING

A university hospital.

METHODS

From medical records, data were collected on glucose measurements during a 100-g, 3-hour OGTT, as well as maternal and fetal outcomes.

RESULTS

Of 119 post-BS pregnant patients included in the study, 55 underwent laparoscopic sleeve gastrectomy, 34 laparoscopic adjustable gastric banding, and 30 laparoscopic Roux-en-Y gastric bypass surgery. Hypoglycemia (<55 mg/dL) was encountered in 59 (49.6%) patients during the OGTT. Among them, the nadir plasma glucose levels occurred 2 hours after glucose ingestion in 25 (42.4%) and after 3 hours in 34 (57.6%), with a median value of 47 (44-52) mg/dL. The risk of hypoglycemia was higher among women with prior laparoscopic Roux-en-Y gastric bypass surgery (83.3%) than among those with prior laparoscopic sleeve gastrectomy (54.5%; P = .009) or laparoscopic adjustable gastric banding (11.8%; P<.0001). Time from surgery to conception was significantly shorter among women with evidence of hypoglycemia during OGTT (median 711 versus 1246 days, P = .002). Compared with patients without evidence of hypoglycemia, patients who experienced hypoglycemia had lower rates of gestational diabetes (P = .03) but higher proportions of low birth weight (P = .01) and small for gestational age infants (P = .03).

CONCLUSIONS

Because hypoglycemia is common during OGTT among post-BS parturients, other diagnostic methods should be considered in this setting. The association found between hypoglycemia and poor fetal growth warrants investigation as to whether interventions to prevent hypoglycemia will improve fetal outcome.

Assessment of glucose regulation in pregnancy after gastric bypass surgery

AIMS/HYPOTHESIS

Roux-en-Y gastric bypass (RYGB) surgery is characterised by glycaemic variability. Prospective studies of glucose metabolism in pregnancy after RYGB are not available, therefore this study aimed to evaluate physiological alterations in glucose metabolism in pregnancy following RYGB.

METHODS

Sixty-three pregnant women (25 who underwent RYGB, 19 non-operated obese control women and 19 normal weight control women) were included. Frequently sampled 3 h OGTTs and 1 h IVGTTs were performed between 24 and 28 weeks of gestation and, in a subgroup, were repeated at 3-6 months after delivery.

RESULTS

We observed major alterations in glucose kinetics during the OGTT, including an early increase in plasma glucose followed by hypoglycaemia in 90% of women who had previously undergone RYGB. The higher degree of glycaemic variability in this group was accompanied by increased insulin, C-peptide and glucagon concentrations after oral glucose load, whereas no differences in insulin response were observed after parenteral glucose administration (RYGB vs normal weight). IVGTT data suggested improved insulin sensitivity (mean difference 0.226 × 10^-4 min^-1 [pmol/l]^-1 [95% CI 0.104, 0.348]; p < 0.001) and disposition index in pregnancies after RYGB when compared with obese control women. However, subtle alterations in insulin action and beta cell function were still observed when comparing women who had undergone RYGB with the normal-weight control group. Moreover, we observed that fetal growth was associated with maternal glucose nadir levels and insulin secretion in offspring of those who had previously undergone RYGB.

CONCLUSIONS/INTERPRETATION

Pregnancies after RYGB are affected by altered postprandial glucose, insulin and C-peptide dynamics. Insulin sensitivity is improved by RYGB, although subtle alterations in beta cell function are observed. Longitudinal studies are needed to assess potential consequences for fetal development and pregnancy outcomes.