Study Design and Data Sources
This population-based cohort study comprised all singleton hospital
livebirths and stillbirths in Ontario, April 1, 2006 to March 31, 2014.
We obtained pregnancy and neonatal outcomes from the Better Outcomes
Registry & Network (BORN) Ontario and Niday Legacy data sets
(www.bornontario.ca/en/data/data-dictionary/legacy-datasets/).
BORN captures more than 99% of hospital births in the province and has
been previously validated for completeness and
accuracy.18 Excluded were pregnancies that resulted in
termination, or a gestational age below 20 complete weeks. Analyses were
restricted to women aged 18 to 60 years. Maternal demographics and
pre-existing health conditions were obtained from the Canadian Institute
for Health Information Discharge Abstract Database (CIHI DAD), National
Ambulatory Care Reporting System (NACRS), Ontario Health Insurance Plan
Claims Database (OHIP), Registered Persons Database (RPDB), Postal Code
Conversion File (PCCF), Linked Delivering Mothers and Newborns
(MOMBABY), Ontario Hypertension Dataset (HYPER), Ontario Diabetes
Dataset (ODD), and the Immigration, Refugees and Citizenship Canada
Permanent Resident (IRCC-PR) database – all existing linked datasets at
ICES (www.ices.on.ca). ICES is an
independent, non-profit research institute funded by an annual grant
from the Ontario Ministry of Health (MOH) and the Ministry of Long-Term
Care (MLTC). As a prescribed entity under Ontario’s privacy legislation,
ICES is authorized to collect and use health care data for the purposes
of health system analysis, evaluation and decision support. Secure
access to these data is governed by policies and procedures that are
approved by the Information and Privacy Commissioner of Ontario.