Effect of Incentives for Self-weighing, Weight Management Goals and Physical Activity Goals on Gaining Weight Healthily During Pregnancy

Gestational weight gain (GWG) is a serious public health concern, and 37% of normal weight, 64% of overweight, and 49-64% of obese women exceed the Institute of Medicine's GWG guidelines. [Deputy 2015] Excessive GWG increases the risk for illnesses, such as gestational diabetes mellitus (GDM) [Cheng 2008, Tovar 2009] which has a long-term impact on the health of both the mother (i.e., increased likelihood of developing metabolic syndrome, [Vohr 2008] type 2 diabetes, [Vambergue 2007, Bellamy 2009] and GDM in subsequent pregnancies [Bottalico 2007] and child [Vohr 2008].

For weight loss, research has found that modest financial incentives are a promising pragmatic strategy for an intervention. Yet, most previous weight management research that has utilized incentives has targeted weight outcomes rather than the behaviors necessary to achieve them. [Paul-Ebhohimhen 2008, Burns 2012] For self-weighing, research has found that daily self-weighing is an important component that supplements behavioral interventions' effort in monitoring and managing gestational weight. [Phelan 2011, Olson 2017, Harrison 2013, Harrison 2014] For physical activity, research has found that physical activity may successfully manage GWG, and a greater adherence to the exercise program is linked to interventions that resulted in weight management success. [McDonald 2016] Thus, a strategy to increase adherence, like financial incentives, may be beneficial.

Consistent with recent research, [Leahey 2015] the investigators will incentivize daily self-weighing and participation in physical activity (i.e., the behaviors) in addition to GWG within the guidelines (i.e., the outcome). Behaviors that negatively impact health often involve immediate benefits and delayed costs (i.e., "eating for two" provides immediate gratification but may lead to excessive GWG), and many interventions involve immediate costs (i.e., the inconvenience and time of an intervention) with delayed and often uncertain benefits of better health years later. [Volpp 2011] Researchers also hypothesize that an approach that offers frequent chances to win small lotteries based on meeting short-term goals will be more effective than a straight pay-for-performance approach (of equal expected value) because people are emotionally attracted to the possibility of winning a lottery. [Loewenstein 2007, Volpp 2008] Therefore, the current study proposes to examine the impact of frequent chances to win small, proximal incentives for meeting short-term goals of self-weighing and physical activity and larger incentives for meeting overall GWG goals by the end of the 36-week gestational period.

To our knowledge, the study is the first to use financial incentives to reduce the likelihood of excessive GWG. This project will support evaluation of the feasibility of this promising approach to decreasing excessive GWG. The incentive strategy is based in theory and focuses on behaviors that has a strong link with gestational weight management (i.e., self-weighing and physical activity) and on an outcome (i.e., achievement of GWG goals), thereby moving the field forward in identifying promising approaches to incorporating financial incentives into gestational weight management. The study design is also pragmatic and has a strong potential for scalability and sustainability within the health care setting.

Pregnant participants (N=40) in their first trimester at an obstetric clinic in Memphis, TN will be randomized in a factorial experiment. Three intervention components will be randomized using a 2 x 2 x 2 factorial design: 1) daily incentives for self-weighing on an electronic scale that will transmit data to the study team (lottery/certain loss), 2) incentives for adhering to the Institute of Medicine's gestational weight gain guidelines based on BMI category (monthly/overall), and 3) incentives for reaching physical activity goals to manage gestational weight gain (yes/no).