Obesity on Vagal Tone, HbA1c and Oxgenation

Thursday, 10 July 2008: 3:35 PM
Rebecca Jo Helmreich, RN, MSN , School of Nursing, University of Texas Health Science Center, Houston, Houston, TX

Learning Objective 1: will be able to identify differences between obese and not obese pregnant women as to vagal tone, HbA1c, oxygenation and blood pressure parameters

Learning Objective 2: will be able to discuss the impact of gestational weight gain on pregnancy outcomes for mother and the infant.


Purpose: to examine the effect of gestational weight gain in obese and non-obese women during pregnancy, on vagal tone, HbA1c, SpO2, and the incidence of pregnancy complications in a UT clinic with 98% women receiving Medicaid assistance.

Methods: The women were comfortably positioned in a semi-sitting position with ECG leads placed to obtain her HR signal. During the observation, subjects were monitored for vagal tone and oxygenation. The blood for HbA1c was drawn after the observation periods. Measurements were completed at three points in time across pregnancy, at 20, 28 and 36 weeks of gestation.

Findings: Preliminary analysis of data has revealed that at 20 weeks gestation the obese group had higher systolic, diastolic and mean arterial blood pressures, higher heart rate and lower heart period than the not obese group. At 28 weeks the blood pressure parameters remained slightly higher for the obese group, but there was no significant differences in heart rate or heart period between the groups. At 36 weeks the not obese group had a greater ratio of weight gain than the not obese group, but other variables were not significantly different between the groups. Vagal tone, HbA1c and oxygenation parameters did not differ between the groups at the three points in time. Whereas the obese group had more incidence of gestational hypertension, the not obese group had higher incidence of perineal lacerations and nuchal cord complications during the birth process.


Conclusion: Although it is known that obesity affects HbA1c and SpO2, little data are available for advanced heart period measurement on vagal responses in relation to HbA1c and oxygenation in obese pregnant women. This dissertation project will lead to further research and may impact clinical practice, leading to interventions that promote vagal responses and positive pregnancy outcomes for mothers and infants.