Fresh Start, a postpartum weight loss intervention for diverse low-income women: design and methods for a randomized clinical trial

This 2-arm randomized controlled trial targeted enrollment of postpartum women between 6 weeks and 6 months after childbirth and compared the narrative-based Fresh Start intervention (n = 60) to a condition consisting of print materials and access to exercise facilities (n = 60). In-person measures were collected at baseline and at 6 and 12 months following the 8-week intensive intervention phase. The study protocol received approval from the Institutional Review Board of the University of Massachusetts Medical School and the Board of Directors of the Family Health Center of Worcester.

Study participants were 139 clients served by 5 WIC clinics in Worcester, MA. Eligibility criteria included: 1) childbirth in the previous 6 weeks to 6 months; 2) age 18 and over; 3) body mass index (BMI) ≥ 27 kg/m²; 4) English-speaking; and 5) obstetric provider approval for participation in the diet and physical activity components of the intervention and weight loss. Exclusions included: 1) being unable or unwilling to give informed consent; 2) being pregnant or planning to become pregnant within the following 24 months; 3) having a psychiatric illness which limits ability to participate; 4) taking a medication that causes weight changes; 5) having no telephone; and 6) planning to move out of the area within the study period.

During routine visits, WIC providers completed a checklist of selected study eligibility criteria (i.e., BMI, date of delivery, age ≥ 18 years, English speaking, ability to consent) to identify potentially eligible clients based on chart information and gave a study fact sheet to the women and inquired about their interest in learning more about the study if they were potentially eligible. Interested women were asked to provide their contact information. Potentially eligible and interested women were then contacted by the study recruiter via telephone to explain the study further and ascertain interest. If verbal consent was provided, additional eligibility screening was conducted (i.e., comfortable speaking in English, plans to reside in the study area over the following 1.5 years, not pregnant or planning to become pregnant, no self-reported health reasons precluding physical activity or calorie restriction, able to attend sessions if randomized to the group intervention condition). Potentially eligible women were scheduled for a study visit at which women were consented for confirmation of BMI eligibility. Eligible and interested women were required to provide written consent for study participation prior to completing the baseline assessment measures. Upon receipt of health care provider approval, women were then randomized to the intervention or the control condition. Baseline characteristics of the study sample are shown in Table 1.

The Fresh Start intervention protocol included eight in-person 90-min weekly group sessions (intensive phase) followed by 9 monthly individual telephone follow-up calls. A WIC program nutritionist implemented the group intervention sessions and calls following a detailed provider manual. The nutritionist was trained in behavioral weight loss strategies, principles of motivational interviewing and the use of the Fresh Start intervention tools. A WIC assistant made reminder calls prior to each session, conducted weigh-ins at the beginning of each session and assisted participants with recording and graphing their weight in a program sheet. The weight loss and associated behavioral objectives included weight loss of 1–2 lb per week by working toward a goal of consuming approximately 1500 and 2000 calories for non-breastfeeding and breastfeeding mothers, respectively, and walking 10,000 steps (or equivalent) per day.

The group sessions were interactive and built on one another. Participants were instructed to track their physical activity, diet and weight in between sessions. Sessions began with a review of the participants’ records since the previous session and discussion of successes and challenges to goal achievement, followed by a review of the previous session. A storytelling video relevant to the session topic (topics depicted in Table 2) was then shown, followed by a guided discussion that intended to highlight the women’s experiences regarding the topic being presented. Group discussions were intended to promote modeling opportunities among the women by highlighting similarities among women and exploration of challenges to behavior change and successful strategies to overcome them. Sessions also sought to promote support among participants (i.e., encouragement to exercise together). All sessions concluded with goal-setting.

Supplemental print materials were adapted from the DPP, and included: a workbook with key session topics, and content and graphics relevant to young mothers (e.g. a list of weight loss motivations for new mothers, illustrations depicting the concept of energy balance, weekly menus with shopping list; a physical activity/exercise menu); a food and activity guide to facilitate tracking of energy intake and expenditure; goal-setting forms; and self-monitoring sheets for tracking daily weight and energy intake and expenditure. Participants were provided with a scale, measuring cups and spoons, a step counter, and access to the local YWCA fitness facilities through a corporate 12-month membership purchased by the study. Participants were encouraged to attend the sessions with their infants and babysitting was provided on-site for older children. At each session, a healthy 500-calorie meal was provided for participants and their children. At the monthly calls, the nutritionist reviewed the participant’s goal attainment and weight loss progress, explored successes and challenges, reviewed any relevant content from the group sessions, and assisted the participant in setting new goals. No new content, strategies or narratives were introduced during the follow-up phase.

The comparison condition was a self-directed intervention in which the Fresh Start print materials were delivered by mail to participants at the outset, along with access to the YWCA via a membership similar to that of the participants in the group intervention. While there is no evidence to support that self-directed or print-based interventions impact weight loss [34, 35], the comparison condition was chosen in order to improve recruitment through the promise of receiving some type of program and to improve retention through maintaining ongoing contact [34, 35].

Table 3 describes the study measures. The primary outcomes were change in weight and BMI. Secondary outcomes were waist circumference, blood pressure, physical activity and diet. Surveys additionally collected information on participant psychosocial and socio-demographic characteristics. Because of threat to contamination, we included a series of questions asking about participants’ potential knowledge of and discussions with other members of the study in the follow-up surveys. Surveys were verbally administered by trained research staff to ensure a higher completion rate given varying literacy levels of participants. In addition, the study examined potential external validity and sustainability of the Fresh Start intervention on measures of reach, adoption, implementation and maintenance, consistent with the RE-AIM framework [36].

Strategies used to maximize participant retention included: request for two alternate telephone numbers; use of personalized letters mailed to non-responding participants encouraging them to call the study coordinator to discuss their status; use of motivational messages to re-kindle original motivations to join the study; provision of incentives after each assessment; and written consent from participants’ to update their contact information through the WIC database if needed. To facilitate timely assessments, a tracking system alerted assessors about participants due for follow-up measures.

Analysis to test the study hypotheses will be conducted in Spring, 2017 when the 12-month follow-up data collection is completed. The longitudinal aspect of the design involves repeated measures at three time points (baseline, and 6 and 12 months post-intensive intervention). To accommodate the correlation between baseline and subsequent time points we plan mixed models regression for primary and secondary analyses. The main predictors of the model include intervention indicator, time points, and the interaction term between intervention indicator and time points. The treatment effects will be evaluated by testing the interaction term of time and the indicator of intervention. We will use exploratory graphical analysis to examine the relationship of the outcome of interest and baseline factors not in balance to determine the functional form of the model fit. Upon determining the best models, we will then include an indicator of the intervention group to estimate and test the effect of the intervention. Model building strategies described by Harrell [37] will be used to build the multivariable models. There is always the chance that some unmeasured confounder could impact on the results. We will estimate the strength of the confounding that would be necessary to eliminate any measured differences between intervention and comparison groups through sensitivity analyses [38, 39]. We will explore site-level effects by estimating random effects models, although we do not anticipate such an effect.

All primary analyses will be conducted on an “intent-to-treat” basis with each patient enrolled in the intervention group analyzed as part of the group, regardless of engagement with the intervention. Additionally, multiple imputation methods will be used to account for those lost at the follow-up sessions.

Planned analyses also include assessing the potential external validity and sustainability of the Fresh Start intervention on measures of reach, adoption, implementation and maintenance, as described in Table 3. Descriptive statistics (i.e. counts, proportions, means) will be used to describe each of these measures.

A center-wide Data Safety Monitoring Board (DSMB) was convened. Because a DSMB was not required by the funder and The Fresh Start project was deemed to be of low risk to participants, the DSMB was comfortable in leaving oversight of the project to the local IRB, the Administrative Core of the center, and the Internal and External advisory committees. The DSMB did make itself available on an as-needed basis.