Jon Barrett

Dr. Jon Barrett


Research Focus & Metrics

Academic Career Length

27Years (2000-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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3 October 2013 in New England Journal of Medicine
Verified
Journal Article
Closed access
PDF file
Jon BarrettJon Barrett
Jon Barrett
MHMary E. Hannah
Mary E. Hannah
EHEileen K. Hutton
Eileen K. Hutton
AWAndrew R. Willan
Andrew R. Willan
AAAlexander C. Allen
Alexander C. Allen
EAElizabeth V. Asztalos
Elizabeth V. Asztalos
Twin birth is associated with a higher risk of adverse perinatal outcomes than singleton birth. It is unclear whether planned cesarean section results in a lower risk of adverse outcomes than planned vaginal delivery in twin pregnancy. We randomly assigned women between 32 weeks 0 days and 38 weeks 6 days of gestation with twin pregnancy and with the first twin in the cephalic presentation to planned cesarean section or planned vaginal delivery with cesarean only if indicated. Elective delivery was planned between 37 weeks 5 days and 38 weeks 6 days of gestation. The primary outcome was a composite of fetal or neonatal death or serious neonatal morbidity, with the fetus or infant as the unit of analysis for the statistical comparison. A total of 1398 women (2795 fetuses) were randomly assigned to planned cesarean delivery and 1406 women (2812 fetuses) to planned vaginal delivery. The rate of cesarean delivery was 90.7% in the planned-cesarean-delivery group and 43.8% in the planned-vaginal-delivery group. Women in the planned-cesarean-delivery group delivered earlier than did those in the planned-vaginal-delivery group (mean number of days from randomization to delivery, 12.4 vs. 13.3; P=0.04). There was no significant difference in the composite primary outcome between the planned-cesarean-delivery group and the planned-vaginal-delivery group (2.2% and 1.9%, respectively; odds ratio with planned cesarean delivery, 1.16; 95% confidence interval, 0.77 to 1.74; P=0.49). In twin pregnancy between 32 weeks 0 days and 38 weeks 6 days of gestation, with the first twin in the cephalic presentation, planned cesarean delivery did not significantly decrease or increase the risk of fetal or neonatal death or serious neonatal morbidity, as compared with planned vaginal delivery. (Funded by the Canadian Institutes of Health Research; ClinicalTrials.gov number, NCT00187369; Current Controlled Trials number, ISRCTN74420086.)

19 July 2016 in BMC Pregnancy and Childbirth
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Journal Article
Open access
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OGon behalf of the MiTy Collaborative Group
on behalf of the MiTy Collaborative Group
DFDenice S. Feig
Denice S. Feig
KMKellie Murphy
Kellie Murphy
Elizabeth AsztalosElizabeth Asztalos
Elizabeth Asztalos
GTGeorge A. Tomlinson
George A. Tomlinson
Jon BarrettJon Barrett
Jon Barrett
The incidence of type 2 diabetes in pregnancy is rising and rates of serious adverse maternal and fetal outcomes remain high. Metformin is a biguanide that is used as first-line treatment for non-pregnant patients with type 2 diabetes. We hypothesize that metformin use in pregnancy, as an adjunct to insulin, will decrease adverse outcomes by reducing maternal hyperglycemia, maternal insulin doses, maternal weight gain and gestational hypertension/pre-eclampsia. In addition, since metformin crosses the placenta, metformin treatment of the fetus may have a direct beneficial effect on neonatal outcomes. Our aim is to compare the effectiveness of the addition of metformin to insulin, to standard care (insulin plus placebo) in women with type 2 diabetes in pregnancy. The MiTy trial is a multi-centre randomized trial currently enrolling pregnant women with type 2 diabetes, who are on insulin, between the ages of 18–45, with a gestational age of 6 weeks 0 days to 22 weeks 6 days. In this randomized, double-masked, parallel placebo-controlled trial, after giving informed consent, women are randomized to receive either metformin 1,000 mg twice daily or placebo twice daily. A web-based block randomization system is used to assign women to metformin or placebo in a 1:1 ratio, stratified for site and body mass index. The primary outcome is a composite neonatal outcome of pregnancy loss, preterm birth, birth injury, moderate/severe respiratory distress, neonatal hypoglycemia, or neonatal intensive care unit admission longer than 24 h. Secondary outcomes are large for gestational age, cord blood gas pH < 7.0, congenital anomalies, hyperbilirubinemia, sepsis, hyperinsulinemia, shoulder dystocia, fetal fat mass, as well as maternal outcomes: maternal weight gain, maternal insulin doses, maternal glycemic control, maternal hypoglycemia, gestational hypertension, preeclampsia, cesarean section, number of hospitalizations during pregnancy, and duration of hospital stays. The trial aims to enroll 500 participants. The results of this trial will inform endocrinologists, obstetricians, family doctors, and other healthcare professionals caring for women with type 2 diabetes in pregnancy, as to the benefits of adding metformin to insulin in this high risk population. ClinicalTrials.gov Identifier: no. NCT01353391 . Registered February 6, 2009.

4 March 2022 in American Journal of Obstetrics and Gynecology
Verified
Journal Article
Closed access
SRStefania Ronzoni
Stefania Ronzoni
TCTeresa Cobo
Teresa Cobo
RDRohan D'Souza
Rohan D'Souza
EAElizabeth Asztalos
Elizabeth Asztalos
SOSusan E. O’rInn
Susan E. O’rInn
MPMontse Palacio
Montse Palacio

1 March 2016 in American Journal of Obstetrics and Gynecology
Verified
Journal Article
Closed access
Elizabeth AsztalosElizabeth Asztalos
Elizabeth Asztalos
MHMary E. Hannah
Mary E. Hannah
EHEileen K. Hutton
Eileen K. Hutton
AWAndrew R. Willan
Andrew R. Willan
AAAlexander C. Allen
Alexander C. Allen
Jon BarrettJon Barrett
Jon Barrett

12 February 2020 in BMC Pregnancy and Childbirth
Verified
Journal Article
Open access
PDF file
BMBeth Murray-Davis
Beth Murray-Davis
HBHoward Berger
Howard Berger
NMNir Melamed
Nir Melamed
KMKarizma Mawjee
Karizma Mawjee
MSMaisah Syed
Maisah Syed
SMSarah D. McDonald
Sarah D. McDonald
Background: Inappropriate gestational weight gain in pregnancy may negatively impact health outcomes for mothers and babies. While optimal gestational weight gain is often not acheived, effective counselling by antenatal health care providers is recommended. It is not known if gestational weight gain counselling practices differ by type of antenatal health care provider, namely, family physicians, midwives and obstetricians, and what barriers impede the delivery of such counselling. The objective of this study was to understand the counselling of family physicians, midwives and obstetricians in Ontario and what factors act as barriers and enablers to the provision of counselling about GWG. Methods: Semi-structured interviews were conducted with seven family physicians, six midwives and five obstetricians in Ontario, Canada, where pregnancy care is universally covered. Convenience and purposive sampling techniques were employed. A grounded theory approach was used for data analysis. Codes, categories and themes were generated using NVIVO software. Results: Providers reported that they offered gestational weight gain counselling to all patients early in pregnancy. Counselling topics included gestational weight gain targets, nutrition & exercise, gestational diabetes prevention, while dispelling misconceptions about gestational weight gain. Most do not routinely address the adverse outcomes linked to gestational weight gain, or daily caloric intake goals for pregnancy. The health care providers all faced similar barriers to counselling including patient attitudes, social and cultural issues, and accessibility of resources. Patient enthusiasm and access to a dietician motivated health care providers to provide more in-depth gestational weight gain counselling. Conclusion: Reported gestational weight gain counselling practices were similar between midwives, obstetricians and family physicians. Antenatal knowledge translation tools for patients and health care providers are needed, and would seem to be suitable for use across all three types of health care provider specialties.

1 February 2014 in Best Practice & Research Clinical Obstetrics & Gynaecology
Verified
Journal Article
Closed access
Jon BarrettJon Barrett
Jon Barrett