A Scoping Review of Perinatal Outcomes for Canadian Individuals with Obesity 1980–2020

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/m2) 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.