Exercise and healthy eating are integral parts of a comprehensive healthy lifestyle intervention during pregnancy. Women who volunteer to participate in such an intervention in early to mid-pregnancy may already be practicing healthy lifestyle habits such as walking 10,000 steps/day (active), and consuming 1800-2252 kilocalories/day (kcal), whereas most pregnant woman walk on average 3000-7000 steps/day (sedentary to low active) and consume 1882-2789 kcal/day. As such, intervention participants may not be representative of the general population of pregnant women, especially relating to exercise. PURPOSE: To assess the baseline exercise and nutrition patterns of pregnant women who enrol in a healthy lifestyle intervention in London, Canada. METHODS: Pregnant women who had self-selected to participate in a nutrition and exercise intervention completed a baseline (12-18 weeks gestation) 3-day step count log and 3-day food intake record (3dFR). Step counts were recorded over 3 consecutive days using a hip-worn pedometer or a wrist-worn activity tracker, and an average was calculated. The 3dFR was completed over the same 3 consecutive days and was analyzed for average energy intake (kcal) using Nutritionist Pro (NP; Axxya Systems). Measured height and self-reported pre-pregnancy weight were used to calculate pre-pregnancy body mass index (BMI). Gestational age at study entry and maternal age were also collected. RESULTS: Ninety-seven pregnant women chose to participate in a healthy lifestyle intervention study and completed both the 3-day step count log and 3dFR at baseline. At study entry, mean daily steps were 7399±2741 (low to above normal range) and energy intake was 2305±634 kcal/day (within to above normal range). Pre-pregnancy BMI was 26.2±5 kg/m² (overweight), gestational age was 15±3 weeks, and maternal age was 32±4 years. CONCLUSION: Many pregnant women who self-select to participate in a lifestyle intervention in early to mid-pregnancy may already have healthy patterns of exercise and to a lesser extent nutrition. To achieve a more representative sample of pregnant women, interventions could be performed in a clinical setting, which may allow for better identification of effective behaviour change strategies to promote and maintain healthy exercise and nutrition patterns during pregnancy.