Gestational Weight and Incentive Research Study

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).

Potential participants will be identified by the clinics' health professionals (i.e., nurses, obstetricians) at their pregnancy confirmation visit or will be self-identified through recruitment materials posted in the obstetric clinic (e.g., exam rooms, lobby and bathrooms). They will encouraged to contact the study team if they wish to learn more about the study and potentially enroll in the study. Upon recruitment, individuals who are interested in learning more about the study will be directed to the Way to Health web portal. Upon reaching the portal, potential participants will be asked to create an account and will then be informed of the details of the study, including its objectives, duration, requirements, and financial payments. If participants are still interested in participating, the Way to Health portal will take them through an automated online informed consent. Potential participants who click a clearly delineated button stating that they agree to participate in the study will be considered to have consented to enroll. After consenting, participants will complete an online questionnaire to determine their eligibility. Eligible participants will first answer a few questions about the number of pregnancies they have prior to the current one, age, annual household income, marital status, employment status, household size, education level, race, and ethnicity. Then, they will be randomized to one of the study arms and led through an automated description of the details specific to that arm. Participants will be provided with details regarding how to contact the research team via email or phone at any time if they subsequently wish to withdraw from the study. This contact information will remain easily accessible via the participants' individual Way to Health web portal dashboards throughout the study.

Participants will be randomized to one of 8 conditions, with combinations of 3 different components of incentive for GWG management and physical activity. Participants will be asked to complete daily self-weighing using the scale provided by the study, as well as wear a physical activity tracker.

Participants randomized to an arm that contains the self-weighing (lottery) component will be asked to pick a number between 00 and 99 at randomization, and will be informed that there will be a daily lottery, for which they will be eligible if they have weighed themselves in the previous day on the Withings e-scale. Then, for each day of their pregnancy, participants will be informed of the study's randomly-generated winning lottery number. Participants will be notified about the results of the lottery.

Participants randomized to an arm that contains the self-weighing (certain loss) component will have a portion of their incentives deducted from a weekly total.

Participants randomized to an arm that contains the monthly GWG incentive component will receive incentives for each month that they have gained within the recommended monthly range for their BMI category for the full months they are enrolled.

Participants randomized to an arm that contains the overall GWG incentive component will receive incentives for weight gain within the recommended range according to the Institute of Medicine gestational weight gain recommendation (based on their body mass index at randomization, adjusted for data collection at 36 weeks).

Participants randomized to an arm that contains the physical activity component will receive a weekly incentive if they achieved a 150 minute physical activity goal for each week based on the guideline from the American College of Obstetricians and Gynecologists (ACOG) [The American College of Obstetricians and Gynecologists 2015].

Measures will be obtained by trained research staff who are blinded to treatment assignment and who will be located within the obstetric clinic.

Baseline measures will be obtained in the first trimester. In-person follow-up data collection visits will be scheduled at gestational week 32 and week 36 (for those still pregnant at 36 weeks). Incentives ($30 for each follow-up visit) will be used to obtain high retention at all follow-up data collection visits. In addition, the research staff will attempt to schedule the data collection visits before or after regular office visits, in order to facilitate retention.

Weekly study meetings, which include retention as a standing agenda item, are also a component of this systematic and comprehensive approach. However, as the investigators will be recruiting participants at <12 weeks gestation (and miscarriage rates are highest in the first trimester), the investigators may lose up to 15% of participants due to miscarriage. [The American College of Obstetricians and Gynecologists 2015] Thus, the investigators project 20% attrition at the final data collection point (36 weeks gestation).

As this is a novel intervention, no related data exist to inform the effect size that might be expected, and as a pilot study, the trial is not powered to detect a significant difference between conditions.

Analyses of GWG (in kg) will be performed using mixed model longitudinal methods. Analyses of the proportion of women with excessive GWG will use logistic regression models to estimate the odds of an intervention participant's GWG falling below or above the guidelines, relative to staying within the recommendations. All of these analyses will inform effect size estimation for the full-scale trial.