Date of Award

Summer 8-15-2015

Author's School

Graduate School of Arts and Sciences

Author's Department

Movement Science

Degree Name

Doctor of Philosophy (PhD)

Degree Type

Dissertation

Abstract

Maternal obesity and physical inactivity during pregnancy are independently associated with unfavorable maternal and neonatal metabolic outcomes. Previous research in non-gravid adults suggests physical activity provides protection from many chronic diseases irrespective of body weight. The primary purposes of this dissertation were to determine the impact of obesity on maternal metabolic health (lipid metabolism, inflammation, insulin resistance) and neonatal metabolic health (adiposity, inflammation, insulin resistance), and to determine if adverse maternal and neonatal metabolic health is improved in obese pregnant women who are physically active during pregnancy compared to sedentary obese women. The secondary purpose of this dissertation was to examine the relationships between maternal and neonatal metabolic health.

Three groups of pregnant women were compared between 32 and 37 weeks gestation (N=50). Groups consisted of: 1) lean women, 2) obese sedentary women, and 3) obese physically active women. Body composition (skinfold anthropometry), physical fitness levels (submaximal cycle test), and physical activity levels (accelerometry) were assessed. Maternal plasma markers of insulin resistance (Homeostatic Model Assessment-Insulin Resistance (HOMA-IR)) and systemic inflammation (C – reactive protein) were measured at rest. Lipid oxidation rate and lipolysis were measured at baseline, during a 30-minute bout of low-intensity exercise, and during a 1-hour recovery period. Cord blood was collected at parturition to measure neonatal plasma insulin resistance, inflammation, and free fatty acid concentration. Neonatal body composition was measured 24-48 hours postpartum via skinfold anthropometry and air displacement plethysmography.

In Chapter 2, maternal and neonatal outcomes were compared between lean and obese pregnant women. Obese pregnant women had higher maternal inflammation, insulin resistance, and lipid oxidation rates. Maternal lipid oxidation rate and inflammation were positively correlated. Maternal inflammation was positively correlated to insulin resistance and blood pressure. Therefore, lipid metabolism may be contributing to inflammation and subsequent insulin resistance and hypertension in obese pregnant women.

In Chapter 3, maternal and neonatal outcomes were compared between obese sedentary and obese physically active pregnant women. Physically active obese women had lower systemic inflammation compared to sedentary obese women; thus, regular physical activity may improve inflammation in obese pregnant women.

In Chapter 4, the relationships between maternal and neonatal metabolic outcomes were examined. There were no correlations between maternal and neonatal metabolic outcomes across all women in the study. Several relationships between maternal and neonatal outcomes were found when comparing lean or obese women separately, which suggests that the mechanisms linking maternal and neonatal metabolic health are complex and potentially BMI-dependent.

In Chapter 5, the relationship between intensity of physical activity and maternal inflammation was examined. Low-intensity physical activities had the strongest negative correlation to systemic inflammation. Data from Chapter 5 also suggest that small daily increases in low-intensity physical activities may be enough of a stimulus to elicit clinically meaningful reductions in inflammation. Thus, pregnant women should be encouraged to participate in low-intensity physical activities in order to reduce their systemic inflammation and improve their long-term health.

Overall, results from this dissertation project suggest that obesity during pregnancy has unfavorable implications for maternal metabolic health. However, a physically active lifestyle might mitigate these alterations, particularly maternal systemic inflammation. Pregnant women of all body weights should be encouraged to participate in daily physical activity, even low-intensity activity, in order to improve their health and the future health of their offspring.

Language

English (en)

Chair and Committee

William Todd Cade

Committee Members

Alison G Cahill, Michael Mueller, Catherine Lang, David Sinacore, Kevin Yarasheski,

Comments

Permanent URL: https://doi.org/10.7936/K7RF5S73

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