Couple-Based Physical Activity Planning for New Parents: A Randomized Trial.

INTRODUCTION: The demands of parenthood may limit the pursuit of moderate-to-vigorous intensity physical activity (MVPA), establish inactivity patterns into middle age, and lead to long-term poorer health and well-being. The purpose of this study was to examine the efficacy of a couple-based planning skills intervention to support MVPA from baseline (~2 months after birth) up to 6 months later in first-time parents. STUDY DESIGN: Randomized trial. PARTICIPANTS: 264 parents (132 couples) at the 2-month point of parenting their first child. INTERVENTION: Couples were randomized to either an education control (n=58 couples) or an education plus planning condition (n=74 couples). MAIN OUTCOME MEASURES: MVPA was assessed via accelerometry and self-report at baseline, 6 weeks, 3 months, and 6 months. Health-related fitness (aerobic fitness, muscular strength, flexibility) and BMI tests were conducted at baseline and 6 months. Rolling recruitment was between 2014 and 2017. RESULTS: The accelerometry results had large amounts of missing data that were not missing at random, so only self-reported MVPA was analyzed. Dyadic multilevel modeling conducted in 2020 showed that mothers' MVPA had a significant quadratic pattern over time that was similar for both conditions, and BMI decreased while strength and flexibility increased. Fathers did not have significant outcomes. Participants who were not meeting MVPA guidelines at baseline responded to the education plus planning condition with increased MVPA (father B=1.31, mother B=1.14, p<0.05) compared with those who initially met those guidelines. CONCLUSIONS: Mothers may be more responsive than fathers to MVPA interventions in early parenthood. Already active parents likely have little to be gained from additional intervention. Future research is needed to effectively promote MVPA during fatherhood and identify novel ways to sustain PA past the early response to an intervention. TRIAL REGISTRATION: This study is registered at www.clinicaltrials.gov NCT02290808.