Pre-conceptual factors play a significant role in predisposing to caesarean birth. Obesity is associated with failure to initiate labour. In Canada, approximately 15% of women use alcohol or tobacco during pregnancy, which can damage the placenta and compromise the ability of the fetus to tolerate labour. Pre-conception risk factors call for intervention in the public health arena, utilizing the expertise of exercise specialists, nutritionists, behavioural psychologists and other disciplines not commonly associated with maternity research. This theme will conduct studies to study the impact of preconceptual population-based health promotion programs on pregnancy outcomes.