Measurement error of energy intake during pregnancy and its influence on the association between carbohydrate quality and fetal growth Public Deposited

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  • March 21, 2019
  • Nowicki, Eric Michael
    • Affiliation: Gillings School of Global Public Health, Department of Epidemiology
  • Population studies rely on self-reported dietary intake, which is subject to considerable measurement error. A growing body of literature has shown that subjects tend to underreport energy (food) intake, and that underreporting occurs more frequently in certain subgroups, such as women and overweight persons. Further, recent evidence has demonstrated that systematic reporting error in energy intake can seriously distort nutrient risk estimates. Maternal nutrition plays an important role for both the mother and fetus; however results on associations between diet and pregnancy outcomes thus far have been modest or non-existent. One reason may be systematic reporting bias in nutritional data, although very little is known about this error in pregnant populations. Adequate fetal growth is an important predictor of newborn complications, and also contributes to a wide array of health conditions in adolescence and adulthood. Maternal glucose is the main energy substrate for intrauterine growth. The glycemic index (GI) and glycemic load (GL) of dietary carbohydrate, has been shown to alter postprandial glucose and insulin concentrations among healthy pregnant women, and thus may alter glucose substrate levels available for the fetus. Despite this strong biological plausibility, research on the carbohydrate quality of maternal diet and fetal growth remains limited. This dissertation includes two analyses of data from participants in the third phase of the Pregnancy, Infection and Nutrition cohort study (PIN3). The first analysis indicates that measurement error in energy intake is prevalent during pregnancy with 32.8% and 12.9% of subjects reporting intakes that were implausibly low and high, respectively. This error also varied by several maternal characteristics including pregravid body size, which is an important predictor of many pregnancy outcomes. Therefore, determining the nature of measurement error in energy intake may help to improve dietary assessment methodology in reproductive studies and account for bias in the calculation of effect estimates. In the second analysis, no association was observed between carbohydrate quality and fetal growth among generally healthy pregnancies; a null finding that remained after exclusion of participants with implausible energy intakes. Strengths and limitations of this study and the current literature, as well as and recommendations for future research are noted.
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  • In Copyright
  • "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Epidemiology."
  • Siega-Riz, Anna Maria
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  • Chapel Hill, NC
  • Open access

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