While evidence for the most effective approaches for preventing excess GWG is limited, there is stronger support for targeting improved nutrition quality, physical activity and knowledge of GWG goals in interventions [21,22]. Inclusion of behaviour change theory in GWG interventions is also limited [23]; however, it is suggested that studies most closely aligned with effective behavioural lifestyle programmes in non-pregnant populations appear most effective in changing targeted health outcomes [24].Use of health behaviour theories is likely to be important
for conceptualising the complexity of behaviour change,in both planning interventions and evaluating outcomes.