Research Programs

COVID-19 Research

Data collection and research on COVID-19 in pregnancy are needed to fill the many knowledge gaps in this field. We have launched a series of seroprevalence, vertical transmission and surveillance investigations designed to generate rapid, rigorous evidence specific to the impacts of COVID-19 on maternal, fetal and newborn health. 

  1. UNIVERSE-OB Study: We recently implemented a universal screening program to test all pregnant women delivering at The Ottawa Hospital. The purpose of this study was to assess the burden of symptomatic and asymptomatic SARS-CoV-2 infection. Sample collection for this study is now closed and data analysis is underway.
  2. COPE Network Study: In collaboration with the COVID-19 Ontario Pregnancy Event (COPE) Network – a network of 13 obstetrical hospitals in 6 of Ontario’s largest cities – we are generating complete infection and antibody profiles of maternal and newborn tissues to assess the mother-to-infant transmission potential of SARS-CoV-2 among mothers with confirmed or suspected COVID-19. With these data, we will compile in-depth obstetrical profiles of pregnancies affected by COVID-19 to assess clinical characteristics, transmission patterns and maternal and neonatal outcomes associated with infection. Data and sample collection for this study is ongoing.

Our team includes experts in maternal-fetal-medicine, perinatal epidemiology, molecular virology and infectious diseases. Our findings will inform strategies to optimize processes in care and patient counselling and improve health systems management of COVID-19 in pregnancy.  


  • Canadian Institutes for Health Research. Operating Grant: SARS-CoV-2 variants supplement: COVID-19 Rapid Research Funding. Principal Applicants: El-Chaar D. ($50,000 CAD) (2021-2022)
  • The COVID-19 Ontario Pregnancy Event (COPE) Network: Assessing the impact of COVID-19 in pregnancy on maternal, fetal and newborn health. Canadian Institutes for Health Research. Operating Grant: COVID-19 May 2020 Rapid Research Funding Opportunity. Principal Applicants: El-Chaar D, Langlois MA. ($795,559 CAD) (2020-2021)

Folic Acid Supplementation

Folic acid supplementation in the first trimester of pregnancy to prevent neural tube defects (NTDs) is unequivocally recommended worldwide. However, many women exceed the recommended dosing and duration of folic acid supplementation in pregnancy. In 2009, the OMNI Research Group received funding to examine whether high-dose folic acid supplementation throughout pregnancy (4-5.1 mg daily) could lower the incidence of preeclampsia among women at high-risk of the syndrome. The findings from Folic Acid Clinical Trial (FACT) have been published:

  • Wen SW, Rennicks White R, Rybak N, Gaudet LM, Robson S, Hague W, Simms-Stewart D, Carroli G, Smith G, Fraser WD, Wells G, Davidge ST, Kingdom J, Coyle D, Fergusson D, Corsi D, Champagne J, Sabri E, Ramsay T, Willem B, Oudijk M, Walker MC, FACT Collaborating Group. Effect of high dose folic acid supplementation in pregnancy on pre-eclampsia (FACT): double blind, phase III, randomised controlled, international, multicentre trial. BMJ. 2018; 362:k347812 2018. doi: 10.1136/bmj.k3478. 
  • Corsi DJ, Gaudet LM, El-Chaar D, White RR, Rybak N, Harvey A, Muldoon K, Wen SW, Walker M. Effect of high-dose folic acid supplementation on the prevention of preeclampsia in twin pregnancy. J Matern Fetal Neonatal Med. 2020:1-6. doi: 10.1080/14767058.2020.1725882 

We are now conducting additional analyses on FACT data to evaluate the effect of high-dose folic acid supplementation on risk of pre-eclampsia among specific sub-populations (e.g. diabetes, obesity). The global variations in other medication use in pregnancy and their association with obstetrical and neonatal outcomes in this unique, high-risk population are also being examined. 

In addition, our new FACT 4 Child study is examining the effect of folic acid supplementation in pregnancy on the risk of social impairments, executive function, emotional and behavioural problems, and death through prospective follow-up of children born to women who participated in FACT.


  • An epidemiologic research program to improve maternal and child health. Canadian Institutes of Health Research. Foundation Grant. Principal Applicants: Walker MC, Wen SW. ($9,876,973)(2016-2022)
  • Effect of folic acid supplementation in pregnancy on preeclampsia. Canadian Institutes of Health Research. Randomized Controlled Trials. Principal Applicant: Wen SW. ($6,413,579) (2010-2015)

Caresarean Deliveries by Maternal Request

The contribution of cesarean deliveries on maternal request (CDMR) to rising cesarean delivery rates is a subject of ongoing interest in the obstetrical field. Women may prefer CDMR over vaginal deliveries for a number of reasons including scheduling convenience, fear regarding the pain of labor, and anxieties related to possible urinary incontinence and sexual dysfunction after vaginal delivery. There is limited evidence on the short-term risks and benefits of CDMR and existing data are inconsistent. 

We are using an “intention-to-treat” approach to address notable methodological challenges associated with previously published research on this topic. Our goal is to establish determinants of CDMR and assess the short-term maternal and neonatal outcomes of CDMR relative to planned vaginal delivery. We are further examining longer-term neonatal and child outcomes associated with CDMR, including breastfeeding outcomes, upper-respiratory tract infections, childhood asthma and neuro-developmental outcomes.  


  • An epidemiologic research program to improve maternal and child health. Canadian Institutes of Health Research. Foundation Grant. Principal Applicants: Walker MC, Wen SW. ($9,876,973)(2016-2022)

Obesity in Pregnancy

Obesity during pregnancy poses a significant risk to both mother and baby and is becoming increasingly prevalent. Clear evidence for optimal maternity care of this population remains elusive. Two key uncertainties that affect pregnancies complicated by obesity are:  

  1. ideal gestational age for delivery; and  
  2. ideal mode of delivery for patients.  

Elective deliveries, including vaginal delivery following induction of labour and C-section delivery with or without induction of labour, may help to avoid common adverse infant outcomes associated with deliveries among individuals with obesity. However, the inherent risks of elective delivery to both mother and baby must be considered. Induction of labour, particularly in nulliparous women with severe obesity (≥35kg/m²), is often a prolonged process that results in C-sections. Furthermore, the risks of C-section delivery during labour are increased compared to a pre-labour caesarean section. We are using BORN Ontario registry data to conduct population-based retrospective cohort studies that explore the optimal timing and mode of delivery for women across various categories of obesity and gestational weight gain.  

We are also conducting a partially randomized preference trial (The MODE Trial) to determine the optimal mode of delivery for improving health outcomes for individuals with obesity and their babies. These findings will be used to inform development of a large-scale study that will provide definitive evidence on the optimal care for these women and facilitate patient counselling so that an informed decision can be made. 


  • An epidemiologic research program to improve maternal and child health. Canadian Institutes of Health Research. Foundation Grant. Principal Applicants: Walker MC, Wen SW. ($9,876,973)(2016-2022)
  • OaK 2016-2021: Investigating Contemporary Topics in OB/MFM. Canadian Institutes of Health Research. Team Grant: Clinician-Investigator Teams in Obstetrics & Maternal-Fetal Medicine. Principal Applicants: Gaudet LM, Velez MDP. ($736,960) (2016-2020)

Cannabis and Other Substance Use in Pregnancy

Even prior to legalization, cannabis use has been increasing in Canada, including among pregnant Canadian women. Although we anticipate further increases because of greater availability of cannabis and low perceptions of harm, there is a lack of conclusive evidence on the short-term outcomes and long-term sequelae of exposed children.  

Using provincial data from BORN Ontario and ICES, we are conducting population-based cohort studies to examine pregnancy, neonatal and childhood health outcomes following exposure to cannabis and other substances. We are using these data to evaluate patterns in cannabis and other substance use in pregnant women in Ontario, and the association between substance use in pregnancy and pregnancy and newborn outcomes including preterm birth, birthweight and newborn admission to neonatal intensive care units and re-hospitalization. We are also exploring the longer-term health outcomes of children exposed to cannabis and other substances in pregnancy and through breastfeeding and evaluating the knowledge, attitudes and practices regarding cannabis use in pregnancy among Canadians. 

The findings from this research program will yield important results to assist in shaping comprehensive policy and public health messaging for Canadian women and their health care providers.

Funding :

  • Vaping in Canada: Investigating the geographic distribution and sociodemographic correlates of e-cigarette use. Canadian Institutes for Health Research. Project Grant:  Priority Announcement: Population and Public Health – Early Career Investigator. Principal Applicants: Corsi DJ, Lippert A. ($100,000 CAD) (2021)
  • Pan-Canadian network to investigate cannabis use in pregnancy and neurodevelopmental outcomes in children. Canadian Institutes for Health Research. Team Grant: Cannabis Research in Priority Areas – Neurodevelopment. Principal Applicants: Corsi DJ, Janus M. [CA3 – 170126] ($1,495,716 CAD) (2020-2024)
  • There may be a time and a place, but is pregnancy one? Weeding out the myths from the facts to help make informed choices about cannabis use in pregnancy. Canadian Institutes for Health Research. IHDCYH Talks Video Competition [201910IHT-431699-193718] Principal Applicant: Corsi D. ($750 CAD) (2020)
  • Influence of cannabis exposure in pregnancy on offspring perinatal and childhood health outcomes: a population-based birth cohort. Canadian Institutes for Health Research. Catalyst Grant: Population Health Intervention Research on the Legalization and Regulation of Non-Medical Cannabis in Canada. Principal Applicants: El-Chaar D, Corsi DJ. ($94,691) (2017)

Diabetes in Pregnancy

Gestational diabetes mellitus (GDM) is a form of glucose intolerance characterized by onset or detection during pregnancy. The incidence of GDM is increasing across all provinces and territories. Both pre-existing diabetes and GDM are associated with an increased risk of obstetrical complications and adverse fetal outcomes. In addition, a history of GDM is associated with increased risk of GDM in future pregnancies and development of type-2 diabetes and cardiovascular disease in later life. 

We are characterizing this unique population of women, the patterns of care that they receive during pregnancy, as well as their pregnancy, neonatal and breastfeeding outcomes. We are also examining how the persistence or development of postpartum risk factors are associated with adverse outcomes in later life and in subsequent pregnancies. With this data we will develop predictive models capable of identifying populations at highest risk of GDM and other outcomes associated with hyperglycemia in pregnancy. 

Funding :

  • Gestational weight loss in obese women and risk for adverse perinatal outcomes: a population-based retrospective cohort study. Canadian Institutes for Health Research. Project Grant: Priority Announcement: Data Analysis Using Existing Databases and Cohorts. Principal Applicants: Guo Y, El-Chaar D. ($75,000 CAD) (2021)