Promoting physical activity among postnatal women: the More Active Mums in Stirling (MAMMiS) study

Abstract

ABSTRACT BACKGROUND: Adults benefit from participating in physical activity (PA) for chronic disease prevention and treatment. Postnatal women are encouraged to commence a gradual return to PA 4-6 weeks after giving birth, with participation in line with PA guidelines. The potential benefits of postnatal PA include weight management, improvements in cardiovascular fitness and psychological wellbeing. There has been limited high-quality information about the efficacy, feasibility and acceptability of PA interventions in postnatal women and few studies in the UK. Behavioural counselling interventions informed by behaviour change theory have been shown to successfully increase PA in low-active adults. Physical activity consultations (PACs) use structured and individualised behavioural counselling to enhance individuals’ motivation for change, and improve self-management skills. This approach may support adoption of PA in low-active postnatal women with research demonstrating that modifiable socio-cognitive factors influence PA behaviour. This thesis reports on the efficacy of a postnatal PA intervention, the More Active MuMs in Stirling (MAMMiS) study on change in PA behaviour. Efficacy of the intervention was tested in a randomised controlled trial. The effect on secondary health and wellbeing outcomes and PA cognitions targeted by the intervention and feasibility results are also reported. METHODS: The intervention comprised a face-to-face PAC of around 35-45 minutes and 10-week group pramwalking programme. Non-attenders to the pramwalking group received a support telephone call. A follow-up PAC (15-20 minutes) was delivered after three month assessments. The first PAC involved raising awareness about benefits of PA, developing self-efficacy for change, setting goals and action planning PA, developing strategies for overcoming barriers, encouraging self-monitoring, prompting social support and selecting/changing the environment to support PA. The second PAC involved feedback about changes and preventing a return to sedentary habits. The pramwalking group met weekly for 6 walks of 30-55 minutes at a brisk pace, providing opportunities to demonstrate moderate-intensity walking and to encourage and support PA behaviour change. The control group received an NHS leaflet, which encouraged PA after childbirth. Postnatal women (six weeks to 12 months after childbirth) were identified through a variety of NHS-based and community-based strategies plus local advertisements and word-of-mouth. The primary outcome measure was evaluation of PA behaviour change using the Actigraph GT3X/GT3X+ accelerometer, an objective measure of PA behaviour; self-reported moderate-vigorous physical activity (MVPA) was measured using a recall questionnaire (Seven-Day Physical Activity Recall) and cardiovascular fitness using a submaximal step-test (Chester step-test). Secondary health and wellbeing measures were; anthropometric (i.e. weight and body mass index (BMI)) and body composition (measured using a bioelectrical impedance), psychological wellbeing (measured using the Adapted General Wellbeing Index) and fatigue (measured on a 100-point visual analogue scale). PA cognitions were measured via a questionnaire with constructs adapted from previous studies. All were taken at baseline (prior to randomisation), three and six months follow-up from baseline. Process measures were used to investigate intervention fidelity and feasibility. Acceptability was investigated in a post-trial interviews, conducted by a researcher not involved in the trial. RESULTS: Sixty-five postnatal women (average 33 years old with an infant 24 weeks old) were recruited (77% of those eligible). There was a 91% rate of retention at six months; participants who missed a follow-up assessment were younger (30 versus 34 years old) and had younger infants (21 versus 34 weeks old). Participants were less deprived and older compared with postnatal women in Scotland. Objectively measured PA behaviour did not change in response to the intervention. There was no between-groups difference in change in mean counts/minute from baseline to three months (p=0.35, 95% CI -73.50, 26.17, d=0.22) or three to six months (p=0.57, 95% CI -39.46, 71.18, d=0.13). There was no change in MVPA 7 minutes/day in either group from baseline to three (intervention =-0.70, IQR -9.86, 8.36; control =1.65, IQR -4.79, 8.21) or three to six months (intervention =0, IQR -1.13, 1.10; control =0, IQR -9.86, 8.23), with no between-groups difference baseline to three (p=0.43; r=0.10) or three to six months (p=0.75, r=0.09). Results for relative MVPA were similar. Median steps/day from baseline to three months did not change in the intervention group (0, IQR –1619.44, 1047.94) and increased by 195.95 (IQR -1519.55, 1691.03) among controls. The between-groups difference was non-significant (p=0.37, r=0.18). From three to six month follow-up steps/day increased in the intervention group and not in controls (0, IQR -1147.50, 1303.52), this between-groups difference was also non-significant (p=0.35, r=0.16). From baseline to three months self-reported MVPA declined in the intervention group (15 minutes/week; IQR -111, 15) and increased in the control group (30 minutes/week; IQR –68, 75): a non-significant between-groups difference, with a small effect size (p=0.71, r=0.22). From three to six months a decline in self-reported MVPA was found in controls (53 minutes/week; IQR -41,-101) and no change among the intervention group (0, IQ range -26, 71); a significant between-groups difference with a small effect size (p=0.04, r=0.26). There were no differences between the groups for the change in aerobic capacity from baseline to three months or three to six months with no evidence for change over time in aerobic capacity or fitness category in either group. Change in secondary outcomes did not differ between the groups from baseline to three or three to six months (although fatigue did improve in the intervention group relative to controls from baseline to three months). Considering PA cognitions, outcome expectancies declined in both groups from baseline to three months and continued to decline only in the intervention group from three to six months, a between-groups difference with a small effect size (p=0.03, r=0.26). Self-efficacy increased in the intervention group from baseline to three months and declined in the control group with a small effect size for the between-groups difference (p=0.03, r=-0.27). An increase in action 8 planning was seen among the intervention group but not controls from baseline to three months (p<0.01, r=-0.34). Both groups showed an increase in coping planning and action control; the change was larger among the intervention group relative to controls (i.e. p<0.01, r=0.44, r=0.43, respectively). Increased self-efficacy and action control were maintained from three to six months in the intervention group. Coping planning increased relative to controls (p<0.01, r=0.41) and action planning increased among controls from three to six months (p<0.01, r=0.39). Intervention fidelity and feasibility was good. All intervention participants received the initial PAC and adoption of self-management strategies was high for ‘thinking about the benefits of PA’, ‘action planning’ and ‘self-monitoring’, between baseline and three months. Most participants attended at least one walk (61% attended five or more), 89% of planned walks were conducted with no evidence of poor attendance due to season. Walks were conducted at a brisk pace and met moderate-intensity thresholds. DISCUSSION: MAMMiS aimed to recruit low-active healthy postnatal women to test the efficacy of a PAC and group pramwalking intervention. There was no evidence for an intervention effect on PA or on secondary health and wellbeing outcomes. Compared to previous postnatal studies the study sample were relatively active at baseline, there was large variability in accelerometer-measured PA and evidence for fluctuating PA habits. There were positive impacts of the intervention on PA cognitions, which published studies have shown mediate PA behaviour change and postnatal women perceived benefits from taking part. The intervention was feasible, although due to the sample being older and more affluent compared with the general population of postnatal women in Scotland, this would need to be considered if implementing the intervention. Given the importance of PA for health and the challenges of both engaging postnatal women and for postnatal women wanting to be physically active, the findings from MAMMiS provides important evidence to inform future choices about trial design and intervention approach in postnatal PA promotion trials.b