Planned Behavior Model

Intervention
The main aim of the proposed intervention is to encourage obese pregnant women to be more physically active, in order for them to reduce their excess weight and reach a suitable weight to maintain. The Theory of Planned Behaviour model (TPB) by Ajzen, (1991) will be used to explain the intervention process – this model is one of the most validated models that predict behaviour (Downs & Hausenblas, 2004). These researchers successfully used this model and found that the most salient beliefs were that mood could be elevated by exercise and weight gain was influenced by exercise. The behavioural beliefs (attitude), normative beliefs (subjective norm) and control beliefs (perceived control) of the TPB all determine intention and
behaviour. These three variables of the TPB have been found to explain 40-60% variance in intentions to exercise, and a combination of intention and perceived behavioural control explained a 20-40% variance in exercise behaviour (Hagger, Chatzisarantis & Biddle, 2002).The role of supportive networks (normative beliefs) is significantly likely to lead to a stronger intention to exercise which should be considered when proposing the intervention.
These women have different needs that need to be met; one study found that mood was affected by exercise, so the proposed intervention could use techniques to ensure that the physical activity women undertake warrants a positive mood. Pregnant women who are likely to get tired cannot endure long hours of physical activities, so an intervention would be sure to include shorter sessions of physical activity either individually or within a group. Moreover women of ethnic backgrounds may be deficient in the English language and it is important that they too understand everything that is addressed. Consequently translators could be present during the intervention to offer their services to those who need it.
Primarily, an advertisement will be posted on the local newspapers and Facebook; the 100 who sign up will be required to undergo a screening test certifying that they fit the eligibility requirements; age, BMI 30+, etc.
The selected will receive emails with a forwarded self-report questionnaire pre-intervention; this will ask for their current weight and then measure each of the TBP components (Ajzen, 2002); for behavioural intention there will be a scale ranging from ‘strongly disagree’ to ‘strongly agree’ whereby the women will need to place a check within one of the nine different points that best represents their intentions ‘ I plan to participate in around 30 minutes of physical activity every day for the next month. This will be followed by measures of attitude including different adjective scales ranging from ‘harmful-beneficial,’ ‘pleasant-unpleasant’ etc. ‘For me to partake in around 30 minutes of physical activity daily for a month is.’ The measure of subjective norms will include ‘Most people who are important to me think that’ and another scale ‘I should-I should not’ complete around 30 minutes of physical activity daily, for a month. Finally for perceived behavioural control – measures will include scales covering control and self-efficacy; ‘impossible-possible’ ‘For me to undergo 30 minutes of physical activity for around 30 minutes every day for a month
is.’
The next stage will involve a hour and a half session at a local community centre once every week – for 6 weeks, whereby the first half hour will centre on teaching the group of women about the risks of maternal obesity and importance of reducing the excess weight to benefit their lives and their babies; this will be conducted by a health professional specialised in maternal obesity. The next hour will involve a control task where the women would think about a situation where they felt in control being physically active, and one where they were not in control and think about differences between them (Darker, French, Eves & Sniehotta, 2010) – this is to stimulate motivation to be more physically active, because past behaviours that have been performed are reliable predictors of future behaviour (Ogden, 2012). Afterwards there will be a maternal fitness instructor demonstrating useful activities as well as muscle relaxing exercises ensuring the women partake in them too, while suggesting simple activities women could incorporate into their daily lives. The women will have targets to reach on the day of the classes every week with their pedometers, (2000 steps for the week 1 class) – with the incentive of winning weekly prizes including prams, baby clothes, spa days etc. Targets will be reviewed every week and women will need to think about why they did/did not reach the target and how they could improve for the following week.
Those attending both classes will have their spouses or a significant other contacted (via numbers given during the screening tests), to encourage and support them during the intervention; this will satisfy the subjective norm role of the TPB model. Also because husbands and fiancés were the most common influences on exercise behaviours (Downs & Hausenblas, 2004).There are many behaviour change techniques (Abraham & Michie, 2008) that are going to be used throughout the intervention, in order to encourage the practice of physical activity - some include, general information and that of consequences, specific goal setting, modelling behaviour and contingent rewards which have specifically been useful in encouraging target behaviours in the past (Ranganathan & Lagarde, 2012).

Evaluation
For comparability, looking at the effects of both intervention classes – 50 of the 100 women will partake in both classes – the other 50 will not attend the intervention.
Comparison is necessary to ensure that changes in the 50 women attending the intervention are due to intervention participation itself and no external influences. Questionnaires will be given to all 100 of the women pre-intervention, immediately post intervention and a final one 6 weeks later to see whether the intervention had long-lasting effects for the women who took part, and compare it to the women who did not. Positive changes to attitudes, others’ beliefs and personal control beliefs will be indicative of a successful intervention effect where behavioural intentions were acted upon. Their weight and measure of BMI on each of the three occasions will determine whether they are still obese or have excess weight – a decline would suggest that the intervention was effective in reducing obese pregnant women’s excess weight. The scores from the pedometer will be calculated on the three separate occasions to see whether both groups of women continued to be physically active. A high pedometer score would imply that more physical activity had been
practised.
The evaluation will be carried out by a health psychologist who will reach a suitable conclusion regarding the effectiveness of the intervention in getting pregnant obese women to be more physically active in their lives, and to inform and help towards designing better future interventions accordingly.
Some methodological issues may arise, because external factors such as dieting or stress were not controlled – but may be the cause of reduced weight post intervention rather than the intervention and engagement in physical activity itself. Future interventions can look towards implementing a design which controls for these external factors. Also some women may not have had social support from others as they may have been a single parent/orphan with no relatives; this suggests the subjective norm role of the model will not be satisfied. The intervention could have included a final measure at the 6 week follow up, to discover whether the 50 women (who attended the intervention) believed the intervention was useful, whether they were happy and what they would change/add for a future intervention.