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Objective: To develop twin‐specific outcome‐based oral glucose tolerance test (OGTT) diagnostic thresholds for GDM based on the risk of future maternal type‐2 diabetes. Design: A population‐based retrospective cohort study (2007–2017). Setting: Ontario, Canada. Methods: Nulliparous women with a live singleton (n = 55 361) or twin (n = 1308) birth who underwent testing for gestational diabetes mellitus (GDM) using a 75‐g OGTT in Ontario, Canada (2007–2017). We identified the 75‐g OGTT thresholds in twin pregnancies that were associated with similar incidence rates of future type‐2 diabetes to those associated with the standard OGTT thresholds in singleton pregnancies. Results: For any given 75‐g OGTT value, the incidence rate of future maternal type‐2 diabetes was lower for women with a twin than women with a singleton pregnancy. Using women with a negative OGTT as reference, the risk of future maternal type‐2 diabetes in twin pregnancies with a positive OGTT based on the standard OGTT thresholds (9.86 per 1000 person years, adjusted hazard ratio (aHR) 4.79, 95% CI 2.69–8.51) was lower than for singleton pregnancies with a positive OGTT (18.74 per 1000 person years, aHR 8.22, 95% CI 7.38–9.16). The twin‐specific OGTT fasting, 1‐hour and 2‐hour thresholds identified in the current study based on correlation with future maternal type‐2 diabetes were 5.8 mmol/l (104 mg/dl), 11.8 mmol/l (213 mg/dl) and 10.4 mmol/l (187 mg/dl), respectively. Conclusions: We identified potential twin‐specific OGTT thresholds for GDM that are associated with a similar risk of future type‐2 diabetes to that observed in women diagnosed with GDM in singleton pregnancies based on standard OGTT thresholds. Potential twin‐specific OGTT thresholds for GDM were identified. Potential twin‐specific OGTT thresholds for GDM were identified. [ABSTRACT FROM AUTHOR]

Context: The optimal 50 g-glucose challenge test (GCT) cutoff for the diagnosis of gestational diabetes mellitus (GDM) in twin pregnancies is unknown., Objective: This work aimed to explore the screening accuracy of the 50 g-GCT and its correlation with the risk of large for gestational age (LGA) newborn in twin compared to singleton pregnancies. A population-based retrospective cohort study (2007-2017) was conducted in Ontario, Canada. Participants included patients with a singleton (n = 546 892 [98.4%]) or twin (n = 8832 [1.6%]) birth who underwent screening for GDM using the 50 g-GCT., Methods: We compared the screening accuracy, risk of GDM, and risk of LGA between twin and singleton pregnancies using various 50 g-GCT cutoffs., Results: For any given 50 g-GCT result, the probability of GDM was higher (P = .0.007), whereas the probability of LGA was considerably lower in the twin compared with the singleton group, even when a twin-specific growth chart was used to diagnose LGA in the twin group (P < .001). The estimated false-positive rate (FPR) for GDM was higher in twin compared with singleton pregnancies irrespective of the 50 g-GCT cutoff used. The cutoff of 8.2 mmol/L (148 mg/dL) in twin pregnancies was associated with an estimated FPR (10.7%-11.1%) that was similar to the FPR associated with the cutoff of 7.8 mmol/L (140 mg/dL) in singleton pregnancies (10.8%)., Conclusion: The screening performance of the 50 g-GCT for GDM and its correlation with LGA differ between twin and singleton pregnancies., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: People whose singleton pregnancy is affected by hypertensive disorders of pregnancy (HDP) are at risk of future cardiovascular disease. It is unclear, however, whether this association can be extrapolated to twin pregnancies. We aimed to compare the association between HDP and future cardiovascular disease after twin and singleton pregnancies., Methods: We conducted a population-based retrospective cohort study that included nulliparous people in Ontario, Canada, 1992-2017. We compared the future risk of cardiovascular disease among pregnant people from the following 4 groups: those who delivered a singleton without HDP (referent) and with HDP, and those who delivered twins either with or without HDP., Results: The populations of the 4 groups were as follows: 1 431 651 pregnant people in the singleton birth without HDP group; 98 631 singleton birth with HDP; 21 046 twin birth without HDP; and 4283 twin birth with HDP. The median duration of follow-up was 13 (interquartile range 7-20) years. The incidence rate of cardiovascular disease was lowest among those with a singleton or twin birth without HDP (0.72 and 0.74 per 1000 person-years, respectively). Compared with people with a singleton birth without HDP, the risk of cardiovascular disease was highest among those with a singleton birth and HDP (1.47 per 1000 person-years; adjusted hazard ratio [HR] 1.81 [95% confidence interval (CI) 1.72-1.90]), followed by people with a twin pregnancy and HDP (1.07 per 1000 person-years; adjusted HR 1.36 [95% CI 1.04-1.77]). The risk of the primary outcome after a twin pregnancy with HDP was lower than that after a singleton pregnancy with HDP (adjusted HR 0.74 [95% CI 0.57-0.97]), when compared directly., Interpretation: In a twin pregnancy, HDP are weaker risk factors for postpartum cardiovascular disease than in a singleton pregnancy., Competing Interests: Competing interests: Jon Barrett reports receiving fees for giving expert testimony on behalf of the Canadian Medical Protective Association. Howard Berger reports receiving human placenta growth factor (PLGF) analysis kits from Roche Diagnostics for a quality improvement study on PLGF use in obstetrics. No other competing interests were declared., (© 2021 CMA Joule Inc. or its licensors.)

Objective: We aimed to quantify the risk of future maternal type 2 diabetes mellitus (T2DM) in women with gestational diabetes mellitus (GDM) based on the type and number of abnormal 75-g oral glucose tolerance test (OGTT) values and the diagnostic criteria used for the diagnosis of GDM., Research Design and Methods: We conducted a population-based retrospective cohort study of all nulliparous women with a live singleton birth who underwent testing for GDM using a 75-g OGTT in Ontario, Canada (2007-2017). We estimated the incidence rate (per 1,000 person-years), overall risk (expressed as adjusted hazard ratio [aHR]), and risk at 5 years after the index pregnancy of future maternal T2DM. Estimates were stratified by the type and number of abnormal OGTT values, as well as by the diagnostic criteria for GDM (Diabetes Canada [DC] vs. International Association of the Diabetes and Pregnancy Study Groups [IADPSG] criteria)., Results: A total of 55,361 women met the study criteria. The median duration of follow-up was 4.4 (interquartile range 2.8-6.3; maximum 10.3) years. Using women without GDM as reference (incidence rate 2.18 per 1,000 person-years), women with GDM were at an increased risk of future T2DM; this risk was greater when using the DC compared with the IADPSG criteria (incidence rate 18.74 [95% CI 17.58-19.90] vs. 14.07 [95% CI 13.24-14.91] per 1,000 person-years, respectively). The risk of future maternal T2DM increased with the number of abnormal OGTT values and was highest for women with three abnormal values (incidence rate 49.93 per 1,000 person-years; aHR 24.57 [95% CI 21.26-28.39]). The risk of future T2DM was also affected by the type of OGTT abnormality: women with an abnormal fasting value had the greatest risk, whereas women with an abnormal 2-h value had the lowest risk (aHR 14.09 [95% CI 12.46-15.93] vs. 9.22 [95% CI 8.19-10.37], respectively). Similar findings to those described above were observed when the risk of T2DM at a fixed time point of 5 years after the index pregnancy was considered as the outcome of interest., Conclusions: In women with GDM, individualized information regarding the future risk of T2DM can be provided based on the type and number of abnormal OGTT values, as well as the diagnostic criteria used for the diagnosis of GDM., (© 2021 by the American Diabetes Association.)

Background: Among singleton pregnancies, gestational diabetes mellitus is associated with adverse outcomes. In twin pregnancies, this association may be attenuated, given the higher rate of prematurity and the a priori increased risk of some of these complications., Objective: Our aim was to test the hypothesis that gestational diabetes mellitus is less likely to be associated with adverse pregnancy outcomes in twin compared with singleton gestations., Methods: This retrospective cohort study comprised all twin and singleton live births in Ontario, Canada, 2012-2016. Pregnancy outcomes were compared between women with vs without gestational diabetes mellitus, analyzed separately for twin and singleton births. Adjusted risk ratios and 95% confidence intervals were generated using modified Poisson regression, adjusting for maternal age, nulliparity, smoking, race, body mass index, preexisting hypertension, and assisted reproductive technology., Results: A total of 270,843 women with singleton (n = 266,942) and twin (n = 3901) pregnancies met the inclusion criteria. In both the twin and singleton groups, gestational diabetes mellitus was associated with (adjusted risk ratio, [95% confidence interval]) cesarean delivery (1.11 [1.02-1.21] and 1.20 [1.17-1.23], respectively) and preterm birth at <37 0/7 weeks (1.21 [1.08-1.37] and 1.48 [1.39-1.57]) and at <34 0/7 weeks (1.45 [1.03-2.04] and 1.25 [1.06-1.47]). In singletons, but not twins, gestational diabetes mellitus was associated with gestational hypertension (1.66 [1.55-1.77]) and preeclampsia. With respect to neonatal outcomes, gestational diabetes mellitus was associated with birthweight greater than the 90th percentile in both twins and singletons, with the risk being 2-fold higher in twins (2.53 [1.52-4.23] vs 1.18 [1.13-1.23], respectively, P = .004). Gestational diabetes mellitus was associated with jaundice in both twins (1.56 [1.10-2.21]) and singletons (1.49 [1.37-1.62) but was associated with the following complications only in singletons: neonatal intensive care unit admission (1.44 [1.38-1.50]), respiratory morbidity (1.09 [1.02-1.16]), and neonatal hypoglycemia (3.20 [3.01-3.40])., Conclusion: In contrast to singleton pregnancies, gestational diabetes mellitus in twins was not associated with hypertensive complications and certain neonatal morbidities. Still, the current study highlights that gestational diabetes mellitus is associated with some adverse pregnancy outcomes including accelerated fetal growth also in twin pregnancies., (Copyright © 2018 Elsevier Inc. All rights reserved.)