Factors Associated with Prenatal Ultrasound Utilization

Background and objectives Ultrasound is commonly used in pregnancy and serves a very important purpose in maternal and fetal screening and diagnosis. However, when not medically necessary it may have an economic impact and may lead to unnecessary interventions. The purpose of this dissertation was to increase the knowledge about prenatal ultrasound utilization which has not been adequately explored. The specific objectives of this dissertation were to 1) study the relationship between having single versus multiple prenatal care providers and the number of prenatal ultrasounds in the USA, 2) explore the factors associated with the timing of the first prenatal ultrasound in Canada, and 3) assess the relationship between the number of prenatal ultrasounds and primary caesarean delivery in Canada and the USA.

Methods Responses from two national, cross-sectional surveys were analyzed to address these objectives. The two surveys were the Maternity Experiences Survey from Canada and the Listening To Mothers III survey from the USA. Negative binomial (for objective 1), multinomial (objective 2) and binary (for objective 3) logistic regression models were used to analyze the data. The provided survey weights were applied to both surveys to make the data nationally representative. Bootstrap weights were also applied to the analyses involving the Maternity Experiences Survey.

Results The results of objective 1 showed no significant relationship between having single versus multiple prenatal care providers and the number of prenatal ultrasounds in the USA. The findings of objective 2 showed that multiple factors were associated with the timing of prenatal ultrasound in Canada including province of prenatal care, maternal age and country of birth. The results of objective 3 showed a significant relationship between the number of prenatal ultrasounds and caesarean delivery in Canadian multiparas and primiparas as well as in American multiparas.

Conclusions The findings of this dissertation form a baseline of attributes of prenatal ultrasound utilization in Canada and the USA and may be used to inform efforts aimed at the optimization of prenatal ultrasound utilization. Future studies can further investigate these relationships, perhaps using more robust databases that may allow for better control of confounding variables.