Background: Pre-pregnancy obesity has long been associated with a
higher risk of antepartum, intrapartum, and postpartum complications, leading to
classifying all patients within the WHO obese body mass index range (BMI
30 kg/m) as high-risk. Excessive risk classification can lead to
over-treatment and iatrogenic harm. Research supporting these increased risks
comes from a variety of countries with different baseline population health and
perinatal health care systems. Recent research documents that parturients with
high pre-pregnancy BMI can have uncomplicated pregnancies and births. Here, the
relationship between obesity and perinatal outcomes in a Canadian population is
investigated using Canada as a model of a country with stable nutrition
sufficiency and universal access to health care. Methods: We searched
electronic databases PubMed, Ovid MEDLINE, and CINAHL for peer-reviewed articles
in English that examined perinatal outcomes of singleton pregnancies in Canada
between 1980 and 2020 based on pre-pregnancy obesity as the exposure of interest.
Results: The search yielded 1946 results. After full-text screening, 21
articles met criteria for analysis. The impact of obesity on preterm labour,
preterm birth, post-term delivery, labour induction, post-partum hemorrhage, and
parturient morbidity and mortality in Canada remains inconclusive. The risk of
hypertensive disorders, gestational diabetes, shoulder dystocia, and cesarean
section delivery was significantly elevated as BMI increased. Operative vaginal
delivery was less common in those with pre-pregnancy obesity.
Conclusions: Though certain adverse perinatal outcomes are associated
with increasing pre-pregnancy BMI, given the wide range of results and range of
risk values, further research is required to better delineate comorbid risk
factors that contribute to poorer outcomes. Nation-specific outcomes that reflect
the accessibility of perinatal care and population health are a necessary
baseline for the development of accurate health management guidelines.
