The Influence of Pregestational Body Mass Index and Physical Activity Patterns on Maternal, Delivery, and Newborn Outcomes in a Sample of Portuguese Pregnant Women: A Retrospective Cohort Study

Introduction: There is a linear association between pregestational body mass index (BMI) and almost all adverse pregnancy outcomes. Pregnancy is “a window of opportunities” in terms of changing behavior and improving awareness of healthy living. The proper assessment of physical activity levels, during pregnancy, determines trends, health benefits, and their effects over time. This study aims to describe maternal physical activity levels, stratified by pregestational BMI, verify the accomplishment of physical activity recommendations in pregnant women, and correlate pregestational BMI and physical activity accomplishment with maternal, delivery, and neonatal parameters. Methods: A retrospective cohort study was carried out with 103 pregnant women. Physical activity levels were evaluated using a questionnaire and accelerometry. Pregestational BMI was obtained through the Quetelet formula and used the American College of Sports Medicine’s guidelines were used to determine physical activity accomplishment levels. Continuous data were presented as mean and standard deviation and categorical data as numbers and percentages. The F test was used to examine the differences between groups. Results: Pregnant women in the sample spent 42.9% of their time on household activities, and for pregnant women with obesity, 91.5% of the time was spent on sedentary activities. Women with normative BMI had higher levels of moderate-intensity activities. Only 15.8% of participants with obesity reached the international recommendations for physical activity practice and women who accomplished physical activity recommendations gained less weight during pregnancy. A high percentage of pre-obesity and obese pregnant women exceeded the recommendations for gestational weight gain and the gestational diabetes prevalence was higher in the obesity group (p = 0.03 between groups). Regarding delivery and neonatal parameters (Apgar score 1st, Apgar score 5th, birth weight, length and head circumference), no statistical differences were found when adjusted to a gestational week at birth, between BMI (p = 0.58; p = 0.18; p = 0.60; p = 0.34; p = 0.34, respectively) or physical activity (p = 0.12; p = 0.15; p = 0.83; p = 0.70; p = 0.70, respectively) groups. Conclusion: Pregnant women with obesity, exhibit high levels of sedentary behavior, a high prevalence of gestational diabetes, and exceed recommended gestational weight gain. Healthcare professionals have a crucial role in promoting regular physical activity and lifestyle changes before and during pregnancy.