Changing diagnostic criteria for gestational diabetes in Sweden - a stepped wedge national cluster randomised controlled trial - the CDC4G study protocol

The impact of lowering the blood glucose cut-off values in gestational diabetes mellitus on maternal and perinatal outcomes

BACKGROUND

Gestational diabetes mellitus (GDM) is associated with a risk of giving birth to neonates large for gestational age (LGA). Giving birth to a LGA child increases the risk of maternal and perinatal complications. In Sweden, the blood glucose level required for GDM diagnosis has been lowered, resulting in an increased number of women receiving a GDM diagnosis.

PURPOSE

The study aimed to determine whether the change in diagnostic criteria for GDM impacted the incidence of LGA and the assessment of additional maternal and perinatal complications.

METHODS

This retrospective cohort study involved 1237 women diagnosed with GDM. Among them, 92 delivered infants with LGA, 31 delivered infants small for gestational age (SGA), and 1111 delivered infants appropriate for gestational age (AGA). The primary outcome was to compare the incidence of LGA in the different cohorts based on the year they gave birth. Women without GDM at the same periods and their offspring were also analysed.

RESULTS

The incidence of LGA decreased following the change in diagnostic criteria for GDM (OR 0.43; CI 95 %, 0.27-0.68), a result that remained consistent after adjusting for known risk factors (aOR 0.44; CI 95 %, 0.27-0.7).

CONCLUSION

Lowering blood glucose cut-off values was associated with reduced risk of LGA. Compared to the group of mothers without GDM, the intervention did not appear to account for the lower incidence of LGA. Instead, the results suggest a dilution effect, indicating that mothers included after the change were healthier, exhibiting milder diabetes and, therefore, showed improved outcomes.

THE CLINICAL TRIAL REGISTRATION NUMBER

NCT04794283.

Polycystic ovary syndrome and gestational diabetes mellitus association to pregnancy outcomes: A national register-based cohort study

INTRODUCTION

It is well known that both women with polycystic ovary syndrome (PCOS) and women with gestational diabetes mellitus (GDM) have increased risks of adverse pregnancy outcomes, but little is known whether the combination of these two conditions exacerbates the risks. We explored risk estimates for adverse pregnancy outcomes in women with either PCOS or GDM and the combination of both PCOS and GDM.

MATERIAL AND METHODS

Nationwide register-based historical cohort study in Sweden including women who gave birth to singleton infants during 1997-2015 (N = 281 806). The risks of adverse pregnancy outcomes were estimated for women exposed for PCOS-only (n = 40 272), GDM-only (n = 2236), both PCOS and GDM (n = 1036) using multivariable logistic regression analyses. Risks were expressed as odds ratios with 95% confidence intervals (CIs) and adjusted for maternal characteristics, including maternal BMI. Women with neither PCOS nor GDM served as control group. Maternal outcomes were gestational hypertension, preeclampsia, postpartum hemorrhage, and obstetric anal sphincter injury. Neonatal outcomes were preterm birth, stillbirth, shoulder dystocia, born small or large for gestational age, macrosomia, low Apgar score, infant birth trauma, cerebral impact of the infant, neonatal hypoglycemia, meconium aspiration syndrome and respiratory distress.

RESULTS

Based on non-significant PCOS by GDM interaction analyses, we found no evidence that having PCOS adds any extra risk beyond that of having GDM for maternal and neonatal outcomes. For example, the adjusted odds ratio for preeclampsia in women with PCOS-only were 1.18 (95% CI 1.11-1.26), for GDM-only 1.77 (95% CI 1.45-2.15), and for women with PCOS and GDM 1.86 (95% CI 1.46-2.36). Corresponding adjusted odds ratio for preterm birth in women with PCOS-only were 1.34 (95% CI 1.28-1.41), GDM-only 1.64 (95% CI 1.39-1.93), and for women with PCOS and GDM 2.08 (95% CI 1.67-2.58). Women with PCOS had an increased risk of stillbirth compared with the control group (aOR 1.52, 95% CI 1.29-1.80), whereas no increased risk was noted in women with GDM (aOR 0.58, 95% CI 0.24-1.39).

CONCLUSIONS

The combination of PCOS and GDM adds no extra risk beyond that of having GDM alone, for a number of maternal and neonatal outcomes. Nevertheless, PCOS is still an unrecognized risk factor in pregnancy, exemplified by the increased risk of stillbirth.

To neutrally offer or strongly recommend? General practitioners' perspectives on screening for gestational diabetes according to the national guideline in Norway

OBJECTIVE

To explore general practitioners' experiences and reflections on how the current Norwegian guideline for screening for gestational diabetes affects their clinical practice.

DESIGN

A qualitive study in which data were collected through semi-structured focus group interviews and analyzed thematically.

SETTING AND SUBJECTS

Five focus groups conducted in 2020 among GPs in Norway; three interviews took place face-to-face and two were held digitally. The total number of participants was 31.

RESULTS

GPs acknowledged the potential benefits of more extensive screening, but had concerns about the medicalization of pregnancy, stating that some women experienced considerable anxiety. The GPs expressed doubts about the guideline's evidence base but differed in how they interpreted what the guideline was asking them to do. Some offered eligible women the opportunity to be screened, while other set up a screening appointment without consulting the women first. For some, fear of incrimination made them recommend screening without being convinced that it was the right thing for the patient.

CONCLUSIONS

It is unclear whether the guideline for gestational diabetes requires GPs to recommend screening to pregnant women or if they should provide neutral information about the availability of screening. This ambiguity should be addressed, and the guideline evaluated against the core principles of general practice.

Glucose tolerance two years after gestational diabetes classified by old Swedish or new WHO diagnostic criteria

AIM

To explore how introduction of the lower WHO gestational diabetes (GDM) glucose criteria in Sweden affected prediabetes/type-2-diabetes (T2D) incidence two years postpartum.

METHODS

Women included in the PREvention of PostPartum (PREPP) diabetes study were diagnosed with GDM according to EASD 1991 criteria (GDMOLD; n = 93) or only WHO 2013 criteria (GDMWHO; n = 174). Both groups were further stratified by BMI, and BMI-matched normoglycemic pregnancy controls were included (n = 88). Postpartum assessments included oral glucose tolerance tests (OGTT) and anthropometric measurements.

RESULTS

There was a higher postpartum incidence of T2D in GDMOLD versus GDMWHO (P < 0.001). Despite similar BMI, GDMOLD exhibited higher fasting and OGTT glucose levels, lower fat-free-mass, and hip circumference compared to GDMWHO. In normal-weight women, both GDM groups displayed higher HOMA-IR and lower fat-free-mass compared to controls, with GDMOLD additionally showing lower HOMA-β, slower insulin release during OGTT, and worse glucose tolerance than GDMWHO. Among obese women, the main differences were lower fat-free-mass and hip circumference in GDMOLD.

CONCLUSION

The lower glucose cut-offs during pregnancy resulted in lower postpartum incidence of T2D, irrespective of BMI. Fat-free-mass emerged as a key determinant in glucose levels across BMI categories, while lower beta-cell function played a significant role in normal-weight women.

Changing diagnostic criteria for gestational diabetes (CDC4G) in Sweden: A stepped wedge cluster randomised trial

BACKGROUND

The World Health Organisation (WHO) 2013 diagnostic criteria for gestational diabetes mellitus (GDM) has been criticised due to the limited evidence of benefits on pregnancy outcomes in different populations when switching from previously higher glycemic thresholds to the lower WHO-2013 diagnostic criteria. The aim of this study was to determine whether the switch from previous Swedish (SWE-GDM) to the WHO-2013 GDM criteria in Sweden following risk factor-based screening improves pregnancy outcomes.

METHODS AND FINDINGS

A stepped wedge cluster randomised trial was performed between January 1 and December 31, 2018 in 11 clusters (17 delivery units) across Sweden, including all pregnancies under care and excluding preexisting diabetes, gastric bypass surgery, or multifetal pregnancies from the analysis. After implementation of uniform clinical and laboratory guidelines, a number of clusters were randomised to intervention (switch to WHO-2013 GDM criteria) each month from February to November 2018. The primary outcome was large for gestational age (LGA, defined as birth weight >90th percentile). Other secondary and prespecified outcomes included maternal and neonatal birth complications. Primary analysis was by modified intention to treat (mITT), excluding 3 clusters that were randomised before study start but were unable to implement the intervention. Prespecified subgroup analysis was undertaken among those discordant for the definition of GDM. Multilevel mixed regression models were used to compare outcome LGA between WHO-2013 and SWE-GDM groups adjusted for clusters, time periods, and potential confounders. Multiple imputation was used for missing potential confounding variables. In the mITT analysis, 47 080 pregnancies were included with 6 882 (14.6%) oral glucose tolerance tests (OGTTs) performed. The GDM prevalence increased from 595/22 797 (2.6%) to 1 591/24 283 (6.6%) after the intervention. In the mITT population, the switch was associated with no change in primary outcome LGA (2 790/24 209 (11.5%) versus 2 584/22 707 (11.4%)) producing an adjusted risk ratio (aRR) of 0.97 (95% confidence interval 0.91 to 1.02, p = 0.26). In the subgroup, the prevalence of LGA was 273/956 (28.8%) before and 278/1 239 (22.5%) after the switch, aRR 0.87 (95% CI 0.75 to 1.01, p = 0.076). No serious events were reported. Potential limitations of this trial are mainly due to the trial design, including failure to adhere to guidelines within and between the clusters and influences of unidentified temporal variations.

CONCLUSIONS

In this study, implementing the WHO-2013 criteria in Sweden with risk factor-based screening did not significantly reduce LGA prevalence defined as birth weight >90th percentile, in the total population, or in the subgroup discordant for the definition of GDM. Future studies are needed to evaluate the effects of treating different glucose thresholds during pregnancy in different populations, with different screening strategies and clinical management guidelines, to optimise women's and children's health in the short and long term.

TRIAL REGISTRATION

The trial is registered with ISRCTN (41918550).

The WHO 2013 oral glucose tolerance test: The utility of isolated glucose measurements - A retrospective cohort study

OBJECTIVE

The WHO 2013 guidelines recommend screening for gestational diabetes mellitus (GDM) by 3-point oral glucose tolerance test (OGTT). The objective of this retrospective cohort study was to evaluate GDM diagnosed by an isolated high glucose.

STUDY DESIGN

We included pregnant women deemed at risk for GDM were offered GDM screening. We examined the records of 1939 consecutively screened pregnancies at two teaching hospitals in Amsterdam during 2016-2020. Using the WHO 2013 diagnostic criteria, we calculated the proportion of GDM cases diagnosed by isolated abnormal glucose values.

RESULTS

Among those screened in our high risk cohort, GDM incidence was 31.5%. Of the GDM diagnoses, 57.0% were based on an isolated fasting glucose value, 30.9% based on multiple raised glucose measurements, 7.4% on an isolated raised 2-hour glucose and 4.7% on an isolated raised 1-hour glucose. For 1-hour glucose, the number needed to screen was 67 persons for one additional GDM case.

CONCLUSION

The 1-hour glucose in the 3 point OGTT, as suggested by the WHO 2013 guidelines for GDM, contributes only small numbers of GDM cases and a high number needed to screen (67 for 1 additional case in a selective high risk GDM screening strategy), and is likely even less effective in universally screened populations.

Applying WHO2013 diagnostic criteria for gestational diabetes mellitus reveals currently untreated women at increased risk

AIMS

To estimate the prevalence of gestational diabetes mellitus (GDM) in a Danish cohort comparing the current Danish versus the WHO2013 diagnostic criteria, and to evaluate adverse pregnancy outcomes among currently untreated women in the gap between the diagnostic thresholds.

METHODS

Diagnostic testing was performed by a 75 g oral glucose tolerance test (OGTT) at 24-28 weeks' gestation in a cohort of pregnant women. GDM diagnosis was based on the current Danish criterion (2-h glucose ≥ 9.0 mmol/L, GDMDK) and on the WHO2013 criteria (fasting ≥ 5.1, 1 h ≥ 10.0 or 2 h glucose ≥ 8.5 mmol/L, GDMWHO2013). Currently untreated women fulfilling the WHO2013 but not the Danish diagnostic criteria were defined as New-GDM-women (GDMWHO2013-positive and GDMDK-negative). Adverse outcomes risks were calculated using logistic regression.

RESULTS

OGTT was completed by 465 women at a median of 25.7 weeks' gestation. GDMDK prevalence was 2.2% (N = 10) and GDMWHO2013 21.5% (N = 100). New-GDM was present in 19.4% (N = 90), of whom 90.0% had elevated fasting glucose. Pregnancies complicated by New-GDM had higher frequencies of pregnancy-induced hypertension (13.3% vs 4.1%, p = 0.002), large-for-gestational-age infants (22.2% vs 9.9%, p = 0.004), neonatal hypoglycaemia (8.9% vs 1.9%, p = 0.004) and neonatal intensive care unit admission (16.7% vs 5.8%, p = 0.002) compared to pregnancies without GDM.

CONCLUSIONS

GDM prevalence increased tenfold when applying WHO2013 criteria in a Danish population, mainly driven by higher fasting glucose levels. Untreated GDM in the gap between the current Danish and the WHO2013 diagnostic criteria resulted in higher risks of adverse pregnancy outcomes.

Midwives' and Diabetes Nurses' Experience of Screening and Care of Women with Gestational Diabetes Mellitus: A Qualitative Interview Study

Background

Gestational diabetes mellitus (GDM) is increasing and is associated with adverse outcomes for both mother and child. The metabolic demands of pregnancy can reveal a predisposition for type 2 diabetes mellitus (T2DM), and women with a history of GDM are more likely to develop T2DM than women with normoglycemic pregnancies.

Aim

The aim of this study was to explore midwives' and diabetes nurses' experience of their role in screening, care, and follow-up of women with gestational diabetes mellitus and, further, to explore their opinions and thoughts about existing routines and guidelines.

Method

Individual interviews were performed with ten diabetes nurses and eight midwives working in primary and special care. Qualitative content analysis was done according to Graneheim and Lundman.

Results

The analysis of the interviews resulted in the overall theme "An act of balance between normalcy and illness, working for motivation with dilemmas throughout the chain of health care." Difficulties in carrying out the important task of handling GDM while at the same time keeping the pregnancy in focus were central. Women were described as highly motivated to maintain a healthy lifestyle during pregnancy with the baby in mind, but it seemed difficult to maintain this after delivery, and compliance with long-term follow-up with the aim of reducing the risk of T2DM was low. The women came to the first follow-up but did not continue with later contact. This was at a time when the women felt healthy and were focusing on the baby and not themselves. A lack of cooperation and easy access to a dietician and physiotherapist were pointed out as well as a wish for resources such as group activities and multiprofessional teams.

Maternal Risk Factors for Congenital Vertebral Anomalies: A Population-Based Study

BACKGROUND

The spectrum of congenital vertebral defects varies from benign lesions to severe, life-threatening conditions. The etiology and maternal risk factors remain mainly unclear in isolated cases. Hence, we aimed to assess and identify potential maternal risk factors for these anomalies. Based on previous studies, we hypothesized that maternal diabetes, smoking, advanced maternal age, obesity, chronic diseases, and medication used during the first trimester of pregnancy might increase the risk of congenital vertebral malformations.

METHODS

We performed a nationwide register-based case-control study. All cases with vertebral anomalies (including live births, stillbirths, and terminations for fetal anomaly) were identified in the Finnish Register of Congenital Malformations from 1997 to 2016. Five matched controls from the same geographic region were randomly selected for each case. Analyzed maternal risk factors included age, body mass index (BMI), parity, smoking, history of miscarriages, chronic diseases, and prescription drugs dispensed during the first trimester of pregnancy.

RESULTS

In total, 256 cases with diagnosed congenital vertebral anomalies were identified. After excluding 66 malformations associated with known syndromes, 190 nonsyndromic malformation cases were included. These were compared with 950 matched controls. Maternal pregestational diabetes was a significant risk factor for congenital vertebral anomalies (adjusted odds ratio [OR], 7.30 [95% confidence interval (CI), 2.53 to 21.09). Also, rheumatoid arthritis (adjusted OR, 22.91 [95% CI, 2.67 to 196.40]), estrogens (adjusted OR, 5.30 [95% CI, 1.57 to 17.8]), and heparins (adjusted OR, 8.94 [95% CI, 1.38 to 57.9]) were associated with elevated risk. In a sensitivity analysis using imputation, maternal smoking was also significantly associated with an elevated risk (adjusted OR, 1.57 [95% CI, 1.05 to 2.34]).

CONCLUSIONS

Maternal pregestational diabetes and rheumatoid arthritis increased the risk of congenital vertebral anomalies. Also, estrogens and heparins, both of which are frequently used in assisted reproductive technologies, were associated with an increased risk. Sensitivity analysis suggested an increased risk of vertebral anomalies with maternal smoking, warranting further studies.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Follow-up and screening for type-2 diabetes mellitus in women with previous gestational diabetes in primary care

OBJECTIVE

Gestational diabetes mellitus (GDM) is an established risk factor for developing type 2 diabetes mellitus (T2DM) that is possible to prevent by systematic follow-up and preventive measures. The aim of this study was to examine whether women with previous GDM were offered follow-up in primary care, according to Swedish national guidelines.

DESIGN

Retrospective review of electronic medical records.

SETTING

Primary care in southern Sweden, Skåne county.

SUBJECTS

Women who received a GDM diagnosis in 2018 at the Endocrinology department, Skåne University Hospital in Lund. The study population consisted of a total number of 161 patients, whereof 83 patients were included.

MAIN OUTCOME MEASURES

Whether primary care offered follow-up for T2DM after GDM and if any communication took place between secondary and primary care. Furthermore, it was examined whether the quality of the follow-up was in accordance with the national guidelines.

RESULTS

Of the study population, a total of 29% (n = 24) had been followed-up by primary care. In 55% (n = 46) of the cases, there was no communication between secondary and primary care. Plasma glucose was checked in all (n = 20) cases where follow-up could be evaluated. Conversations about lifestyle habits took place in 70% (n = 14) of the cases. Weight and risk factors for cardiovascular disease were controlled in less than half (n = 9) of the patients. Lifestyle advice was offered in two cases and in 24% (n = 20) of the cases an annual check-up was planned.

CONCLUSIONS

The follow-up of women with previous GDM in primary care in southern Sweden was lacking in seven out of 10 cases and showed great potential for improvement.Key PointsGestational diabetes is an established risk factor for developing type 2 diabetes.Earlier research has recognized that risk reduction is possible by systematic follow-up and preventive measures, but the extent of follow-up in primary care in southern Sweden remains unknown.This study demonstrates a lack of follow-up according to national guidelines for women with previous gestational diabetes in primary care in southern Sweden.There is great potential to improve the care of these patients with relatively simple means.

Evolution of Gestational Diabetes Mellitus across Continents in 21st Century

Over the last few decades, several definitions of gestational diabetes mellitus (GDM) have been described. There is currently not enough research to show which way is the best to diagnose GDM. Opinions differ in terms of the optimal screening and diagnostic measures, in part due to the differences in the population risks, the cost-effectiveness considerations, and the lack of an evidence base to support large national screening programs. The basic method for identifying the disease is the measurement of glucose plasma levels which may be determined when fasting, two hours after a meal, or simply at any random time. The currently increasing incidence of diabetes in the whole population, the altering demographics and the presence of lifestyle changes still require better methods of screening for hyperglycemia, especially during pregnancy. The main aim of this review is to focus on the prevalence and modifications to the screening criteria for GDM across all continents in the 21st century. We would like to show the differences in the above issues and correlate them with the geographical situation. Looking at the history of diabetes, we are sure that more than one evolution in GDM diagnosis will occur, due to the development of medicine, appearance of modern technologies, and the dynamic continuation of research.

Diet-Treated Gestational Diabetes Mellitus Is an Underestimated Risk Factor for Adverse Pregnancy Outcomes: A Swedish Population-Based Cohort Study

In Sweden, diet-treated gestational diabetes mellitus (GDM) pregnancies have been managed as low risk. The aim was to evaluate the risk of adverse perinatal outcomes among women with diet-treated GDM compared with the background population and with insulin-treated GDM. This is a population-based cohort study using national register data between 1998 and 2012, before new GDM management guidelines and diagnostic criteria in Sweden were introduced. Singleton pregnancies (n = 1,455,580) without pregestational diabetes were included. Among 14,242 (1.0%) women diagnosed with GDM, 8851 (62.1%) were treated with diet and 5391 (37.9%) with insulin. In logistic regression analysis, the risk was significantly increased in both diet- and insulin-treated groups (vs. background) for large-for-gestational-age newborns, preeclampsia, cesarean section, birth trauma and preterm delivery. The risk was higher in the insulin-treated group (vs. diet) for most outcomes, but perinatal mortality rates neither differed between treatment groups nor compared to the background population. Diet as a treatment for GDM did not normalize pregnancy outcomes. Pregnancies with diet-treated GDM should therefore not be considered as low risk. Whether changes in surveillance and treatment improve outcomes needs to be evaluated.

Association between folic acid use during pregnancy and gestational diabetes mellitus: Two population-based Nordic cohort studies

Introduction

Inconsistent results have been reported on the association between folic acid use in pregnancy and risk of GDM. The aim of this study was to estimate the association between folic acid use and GDM in two population-based Nordic cohorts.

Material and methods

Two cohort studies were conducted using data from the national population registers in Norway (2005–2018, n = 791,709) and Sweden (2006–2016, n = 1,112,817). Logistic regression was used to estimate the associations between GDM and self-reported folic acid use and prescribed folic acid use, compared to non-users, adjusting for covariates. To quantify how potential unmeasured confounders may affect the estimates, E-values were reported. An exposure misclassification bias analysis was also performed.

Results

In Norwegian and Swedish cohorts, adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for maternal self-reported folic acid use were 1.10 (1.06–1.14) and 0.89 (0.85–0.93), with E-values of 1.43 (1.31) and 1.50 (1.36), respectively. For prescribed folic acid use, ORs were 1.33 (1.15–1.53) and 1.56 (1.41–1.74), with E-values of 1.99 (1.57) and 2.49 (2.17), in Norway and Sweden respectively.

Conclusions

The slightly higher or lower odds for GDM in self-reported users of folic acid in Norway and Sweden respectively, are likely not of clinical relevance and recommendations for folic acid use in pregnancy should remain unchanged. The two Nordic cohorts showed different directions of the association between self-reported folic acid use and GDM, but based on bias analysis, exposure misclassification is an unlikely explanation since there may still be differences in prevalence of use and residual confounding. Prescribed folic acid is used by women with specific comorbidities and co-medications, which likely underlies the higher odds for GDM.

Does gestational diabetes increase the risk of maternal kidney disease? A Swedish national cohort study

Background

Gestational diabetes (GDM) is associated with increased risk of type 2 diabetes (T2DM) and cardiovascular disease. It is uncertain whether GDM is independently associated with the risk of chronic kidney disease. The aim was to examine the association between GDM and maternal CKD and end-stage kidney disease (ESKD) and to determine whether this depends on progression to overt T2DM.

Methods

A population-based cohort study was designed using Swedish national registry data. Previous GDM diagnosis was the main exposure, and this was stratified according to whether women developed T2DM after pregnancy. Using Cox regression models, we estimated the risk of CKD (stages 3–5), ESKD and different CKD subtypes (tubulointerstitial, glomerular, hypertensive, diabetic, other).

Findings

There were 1,121,633 women included, of whom 15,595 (1·4%) were diagnosed with GDM. Overall, GDM-diagnosed women were at increased risk of CKD (aHR 1·81, 95% CI 1·54–2·14) and ESKD (aHR 4·52, 95% CI 2·75–7·44). Associations were strongest for diabetic CKD (aHR 8·81, 95% CI 6·36–12·19) and hypertensive CKD (aHR 2·46, 95% CI 1·06–5·69). These associations were largely explained by post-pregnancy T2DM. Among women who had GDM + subsequent T2DM, strong associations were observed (CKD, aHR 21·70, 95% CI 17·17–27·42; ESKD, aHR 112·37, 95% CI 61·22–206·38). But among those with GDM only, associations were non-significant (CKD, aHR 1·11, 95% CI 0·89–1·38; ESKD, aHR 1·58, 95% CI 0·70–3·60 respectively).

Conclusion

Women who experience GDM and subsequent T2DM are at increased risk of developing CKD and ESKD. However, GDM-diagnosed women who never develop overt T2DM have similar risk of future CKD/ESKD to those with uncomplicated pregnancies.

Pregnancy, perinatal and childhood outcomes in women with and without polycystic ovary syndrome and metformin during pregnancy: a nationwide population-based study

BACKGROUND

Polycystic Ovary Syndrome (PCOS) is an endocrine disorder that affects women in reproductive age and represents an unfavourable risk factor for several pregnancy and perinatal outcomes. Despite, no guidelines or pharmaceutical strategies for treating PCOS during pregnancy are available. The aim of this study is to determine the association between polycystic ovary syndrome with or without metformin and the pregnancy, perinatal outcomes as well as the risk of obesity in children born to these mothers.

METHODS

In this nationwide population-based cohort study based in Swedish population, all singleton births (n = 1,016,805) from 686,847 women since 2006 up to 2016 were included. Multivariable logistic and Cox regression modelling with odds ratios (OR) and hazard ratios (HR) and 95% confidence intervals were used to study the association between the exposure of maternal PCOS, metformin during pregnancy (or the combination of both) and: 1) Pregnancy outcomes: preeclampsia, gestational diabetes, caesarean section, and acute caesarean section, 2) Perinatal outcomes: preterm birth, stillbirth, low birth weight, macrosomia, Apgar < 7 at 5 min, small for gestational age and large for gestational age, and 3) Childhood Obesity.

RESULTS

PCOS in women without metformin use during pregnancy was associated with higher risks of preeclampsia (OR = 1.09, 1.02-1.17), gestational diabetes (OR = 1.71, 1.53-1.91) and caesarean section (OR = 1.08, 1.04-1.12), preterm birth (OR = 1.30, 1.23-1.38), low birth weight (OR = 1.29, 1.20-1.38), low Apgar scores (OR = 1.17, 1.05-1.31) and large for gestational age (OR = 1.11, 1.03-1.20). Metformin use during pregnancy (in women without PCOS) was associated with a 29% lower risks of preeclampsia (OR = 0.71, 0.51-0.97), macrosomia and large for gestational age. Obesity was more common among children born to mothers with PCOS without metformin (HR = 1.61, 1.44-1.81); and those with metformin without PCOS (HR = 1.67, 1.05-2.65). PCOS with metformin was not associated with any adverse outcome.

CONCLUSION

PCOS was associated with increased risks of adverse pregnancy and perinatal outcomes and childhood obesity. Metformin appears to reduce these risks in mothers with polycystic ovary syndrome and their children; but may increase the risk of childhood-obesity in children form women without PCOS.

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.

Migrant Middle Eastern women with gestational diabetes seven years after delivery - positive long-term development of beliefs about health and illness shown in follow-up interviews

AIM

No previous studies have been found focusing on the long-term development of beliefs about health, illness and healthcare in migrant women with gestational diabetes mellitus (GDM). The aim of this study was to explore this and the influence on health-related behaviour (i.e. self-care and care seeking) in migrant women from the Middle East living in Sweden seven years after delivery.

BACKGROUND

GDM is increasing, particularly in migrant women. The risk of adverse outcomes of GDM for health can be improved by interventions reducing blood glucose and lifestyle modifications which medicalise the woman's pregnancy due to intensive follow-up and demanding self-care. The reactions might have an enduring impact on the women's long-term psychological and physical health and adoption of preventive health behaviours.

METHOD

Qualitative exploratory study. Semi-structured follow-up interviews 7 years after delivery with women previously interviewed in gestational weeks 34-38 and 3 and 14 months after delivery. Data analysed with qualitative content analysis.

FINDINGS

Health meant freedom from illness, feeling well and living long to be able to care for the children. The present situation was described either positively, changing to a healthier lifestyle, or negatively, with worries about being affected by type 2 diabetes. Beliefs changed among the majority of women, leading to a healthier lifestyle, and they looked positively back at the time when diagnosed and their reactions to it. With few exceptions, they were confident of being aware of future health risks and felt responsible for their own and their children's health/lifestyle. None except those diagnosed with type 2 diabetes had been in contact with healthcare since the last follow-up a year after delivery. Yet, they still would like and need a healthcare model delivering more information, particularly on developing a healthy lifestyle for children, and with regular check-ups also after the first year after delivery.

Comparison of Pregnancy Outcomes Using Different Gestational Diabetes Diagnostic Criteria and Treatment Thresholds in Multiethnic Communities between Two Tertiary Centres in Australian and New Zealand: Do They Make a Difference?

Introduction: Australia, but not New Zealand (NZ), has adopted the International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria to diagnose gestational diabetes (GDM). We compared pregnancy outcomes using these different diagnostic approaches. Method: Prospective data of women with GDM were collected from one NZ (NZ) and one Australian (Aus) hospital between 2007–2018. Aus screening criteria with 2-step risk-based 50 g Glucose Challenge Testing (GCT) followed by 75 g-oral glucose tolerance testing (OGTT): fasting ≥ 5.5, 2-h ≥ 8.0 mmol/L (ADIPS98) changed to a universal OGTT and fasting ≥5.1, 1-h ≥ 10, 2-h ≥ 8.5 mmol/L (IADPSG). NZ used GCT followed by OGTT with fasting ≥ 5.5, 2-h ≥ 9.0 mmol/L (NZSSD); in 2015 adopted a booking HbA1c (NZMOH). Primary outcome was a composite of macrosomia, perinatal death, preterm delivery, neonatal hypoglycaemia, and phototherapy. An Aus subset positive using NZSSD was also defined. RESULTS: The composite outcome odds ratio compared to IADPSG (1788 pregnancies) was higher for NZMOH (934 pregnancies) 2.227 (95%CI: 1.84–2.68), NZSSD (1344 pregnancies) 2.19 (1.83–2.61), and ADIPS98 (3452 pregnancies) 1.91 (1.66–2.20). Composite outcomes were similar between the Aus subset and NZ. Conclusions: The IADPSG diagnostic criteria were associated with the lowest rate of composite outcomes. Earlier NZ screening with HbA1c was not associated with a change in adverse pregnancy outcomes.

Health Economic Evaluation Alongside Stepped Wedge Trials: A Methodological Systematic Review

BACKGROUND

Recently, there has been an increase in use of the stepped wedge trial (SWT) design in the context of health services research, due to its pragmatic and methodological advantages over the parallel group design.

OBJECTIVE

Our objective was to summarise the statistical methods used when conducting economic evaluations alongside SWTs.

METHODS

A systematic literature search extending to February 2020 was conducted in the PubMed, Scopus, Cochrane and National Health Service Economic Evaluation Database (NHS-EED) databases to find and evaluate studies where there was an intention to conduct an economic evaluation alongside an SWT. Studies were assessed for their eligibility, findings, reporting of statistical methods and quality of reporting.

RESULTS

Of the 586 studies retrieved from the literature search, 69 studies were identified and included in this systematic review. A total of 54 studies were published protocols, with eight economic evaluations and seven studies reporting full trial results. Included studies varied in terms of their reporting of statistical methods, in both detail and methodology. There were 34 studies that did not report any statistical methods for the economic evaluation, and only 16 studies reported appropriate methods, mainly using some form of mixed/multilevel model, and two used seemingly unrelated regression. Twelve studies reported the use of generic bootstrap methods and other modelling techniques, whilst the remaining studies failed to appropriately account for clustering, correlation or adjustment for time.

CONCLUSIONS

The use of appropriate statistical methods that account for time, clustering and correlation between costs and outcomes is an important part of SWT health economics analysis, one that will benefit from an effort to communicate the methods available and their performance.

Metformin versus insulin use for treatment of gestational diabetes and delivery by caesarean section: A nationwide Swedish cohort study

OBJECTIVE

Pregnant women who develop gestational diabetes (GDM) are more likely to deliver by caesarean section (CS). Over the last decade, the use of metformin has increased as an alternative to insulin but it's unknown how this shift in treatment has influenced the mode of delivery. Therefore, the aim of this study was to determine the association between metformin use and CS and delivery of a large-for-gestational age (LGA) infant compared to insulin use for GDM.

STUDY DESIGN

The Swedish population health registers were linked to identify pregnant women from 2012 to 2016 without preexisting diabetes and with a first filled prescription of insulin or metformin in trimester 2 or 3 (n = 2467), categorized into those treated with insulin only (88%), metformin only (7.6%), or both insulin and metformin (4.3%). Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI). Analyses were adjusted for relevant covariates and stratified by history of CS.

RESULTS

The proportion of women using metformin to treat GDM increased from 2.5% in 2012 to over 30% in 2016. Comparing insulin only to metformin only use, no association with delivery by CS (adjusted OR 0.79, 95% CI; 0.54-1.16) and lower odds of delivering a LGA infant (adjusted OR 0.44, 95% CI; 0.26-0.76) was found. Treatment with both insulin and metformin was associated with an increased risk of CS (adjusted OR 1.65, 95% CI; 1.06-2.56), which were more often unplanned. Estimates were further elevated in nulliparous (adjusted OR 2.32, 95% CI; 0.95-5.65) and multiparous women with a history of CS (adjusted OR 2.29, 95% CI; 0.60-8.74) but conclusions could not be drawn given the wide CIs.

CONCLUSION

There was no evidence of a higher association of metformin use alone with CS compared to insulin use for treatment of GDM but a protective effect for delivery of a LGA infant was shown. Women requiring treatment with both insulin and metformin had increased odds for delivery by CS which in turn may indicate that the need for the use of both medications to treat GDM suggests a pregnancy at higher risk.

Diagnosis of Gestational Diabetes Mellitus with Point-of-Care Methods for Glucose versus Hospital Laboratory Method Using Isotope Dilution Gas Chromatography-Mass Spectrometry as Reference

BACKGROUND

In Sweden, both glucose analyzers in accredited laboratories and point-of-care glucose devices are used for gestational diabetes mellitus (GDM) diagnosis. The aim of this study was to compare the diagnostic performance of the HemoCue Glucose 201+ (HC201+) and RT (HC201RT) systems with that of the hospital central laboratory hexokinase method (CL) based on lyophilized citrate tubes, using the isotope dilution gas chromatography-mass spectrometry (ID GC-MS) as reference.

METHODS

A 75 g oral glucose tolerance test was performed on 135 women screened positive for GDM. Diagnosis was based on the World Health Organization 2013 diagnostic thresholds for fasting (n = 135), 1 h (n = 135), 1 h (n = 135), 1 h (.

RESULTS

Significantly more women were diagnosed with GDM by HC201+ (80%) and CL (80%) than with the reference (65%, P < 0.001) based on fasting and/or 2 h thresholds, whereas the percentage diagnosed by HC201RT (60%) did not differ significantly from the reference. In Bland-Altman analysis, a positive bias was observed for HC201+ (4.2%) and CL (6.1%) and a negative bias for HC201RT (-1.8%). In the surveillance error grid, 95.9% of the HC201+ values were in the no-risk zone as compared to 98.1% for HC201RT and 97.5% for CL.

CONCLUSIONS

A substantial positive bias was found for CL measurements resulting in overdiagnosis of GDM. Our findings suggest better performance of HC201RT than HC201+ in GDM diagnosis. The results may have possible implications for GDM diagnosis in Sweden and require further elucidation.