Cesarean birth: Examine the risk of cesarean birth after labor induction among women by BMI category.

 Hypothesis 1: Compared to women with normal range body mass index, the odds of cesarean birth following labor induction will be higher with each increase in body mass index category.

 Hypothesis 2: The odds of cesarean birth in women induced with misoprostol will be lower compared to the odds in similar women induced using dinoprostone.

 Hypothesis 3: Women with obesity (in any obesity category) who are induced using mechanical means will have lower odds of cesarean birth than women with obesity (in any obesity category) induced with prostaglandins (misoprostol or dinoprostone).

Assumptions

 The data in the electronic record are accurately recorded

 A rate of 10%-15% adequately represents medically necessary cesarean deliveries in the U.S. population

Conceptual Framework

The Quality Health Outcomes Model (QHOM) will guide the selection and analysis of the variables for the proposed study (Mitchell, Ferketich, & Jennings, 1998; Mitchell

& Lang, 2004). The QHOM has been used to guide the development of outcomes-based databases, interventions, and research (Mitchell et al., 1998). Two functions of the model are to (1) identify variables in clinical research, and (2) provide a framework for

outcomes research and management that compares treatment options as well as organizational or systems-level interventions. The QHOM has been used to measure outcomes in a variety of patient settings including skilled nursing facilities, ambulatory care settings, surgical units, and for inpatient hospitalization (Altares Sarik & Kutney- Lee, 2016; Cohen, Dick, & Stone, 2016; Gerolamo, 2004, 2006).

In previous obstetrics research the QHOM was used to examine the relationships between labor induction and cesarean birth (Mayberry & Gennaro, 2001; Wilson, Effken, & Butler, 2010). In a secondary analysis (n = 62,816) the model was used to determine what variation in cesarean birth rates was due to differences in hospitals, providers, and patients (Wilson et al., 2010). Wilson et al. (2010) found the occurrence of cesarean birth in nulliparous women was related to maternal age, race, education level, the number of prenatal visits, and place of childbirth. Cesarean birth and epidural analgesia, were associated with significant differences in quality health outcomes for women (Mayberry & Gennaro, 2001). Thus, the QHOM is appropriate as a framework to examine the clinical interventions of labor induction processes and outcomes in search of better clinical outcomes for women undergoing induction of labor.

Concepts in the Quality Health Outcomes Model

The QHOM illustrates integration and interaction of four concepts; system characteristics, individual characteristics, interventions, and outcomes (Mitchell et al., 1998). The relationships in the model are circular in nature. With both system

characteristics and individual characteristics acting on the interventions and outcomes in the model. The original model has equal input from both system and individual

characteristics as demonstrated with a bidirectional arrow between the two influences, as well as curved arrows towards the interventions and outcomes.

In the proposed study, the adapted QHOM provides guidance in the selection of variables that may influence the type of birth. The systems characteristics, (hospital size, location and type and provider type), individual characteristics (BMI, age, parity, and cervical status), interventions (the method used for cervical ripening or labor induction) and the outcomes (type of birth) and secondary outcomes (success or failure of the cervical ripening method and the time to birth) as well as maternal and neonatal adverse events (See Figure 2).

System characteristics. The system characteristics as defined by the original theorists are traditional structure and process elements (Mitchell et al., 1998). System characteristics are the characteristics of a structured system, such as a hospital system, or provider network. The hospital size, location, ownership, individual demographics, provider training and skill mix, and technology are among many of the structural elements included in the system characteristics. The system characteristics included in the adapted model for this study are the hospital type, and size.

Individual characteristics. Outcomes in the model may be affected by the characteristics of the individuals who are receiving the interventions (Mitchell et al., 1998). Outcomes research has raised awareness on the important need to adjust

interventions based on individual characteristics, such as general health, demographics, and disease risk factors.

In the proposed study, individual characteristics will be conceptualized as maternal characteristics before cervical ripening. Maternal characteristics of interest include body mass index (BMI), age, parity, and cervical status on admission. The proposed study will examine women undergoing induction of labor who have carried the pregnancy to term (gestational age greater than 37 weeks), have a cephalic presentation (head first presentation), and a singleton pregnancy (one fetus).

Interventions. Clinical interventions are the actions that are altered with the intent of changing other constructs in the model (Mitchell et al., 1998). Interventions are directly or indirectly influenced by system and individual characteristics. The

intervention of interest is induction of labor using either prostaglandins, or mechanical means for cervical ripening.

Outcomes. Outcomes of treatment interventions from general research have been widely based on the Five D’s: death, disability, dissatisfaction, disease, and discomfort before use of this model (Mitchell et al., 1998). The QHOM allows for measurement and analysis of outcomes related to increased health status, increased functionality, and an increase in the quality of life. The primary outcomes of interest are the success or failure of labor induction, which will be measured by the time to birth and type of birth.

Secondary outcomes in the model are the maternal and neonatal adverse events as

complications associated with maternal obesity included post-partum hemorrhage, sepsis, prolonged hospital admission, increased fetal birth weight and fetal distress (Mission et al., 2013).

21

CHAPTER II