Nutrition and exercise behaviour change programs can prevent excessive gestational weight gain (EGWG). The Nutrition and Exercise Lifestyle Intervention Program (NELIP) is a previously published two-behaviour change program which was successful in preventing EGWG across normal weight, overweight and obese pre-pregnancy body mass index (BMI) categories (Ruchat et al. 2012; Mottola et al. 2010), however some women found it difficult to adhere to two lifestyle behaviour changes throughout pregnancy. The proposed pilot randomized controlled trial will address the issue of adherence by identifying the best way to offer a two-behaviour change program (NELIP) to pregnant women to increase the effectiveness of preventing early and total EGWG. Participants will begin the program at <18 weeks gestation and will be randomized to one of three groups: A) Receive both behaviour changes (Nutrition AND Exercise) simultaneously at entrance to the study; B) Receive the nutrition component first followed sequentially by the introduction of exercise at 25 weeks gestation (Nutrition FOLLOWED by Exercise); C) Receive the exercise component first followed sequentially by the introduction of the nutrition component at 25 weeks gestation (Exercise FOLLOWED by Nutrition).

A randomized parallel groups design will be used as a pilot project. Each participant will be medically pre-screened using the PARmed-X for Pregnancy (2015) in early pregnancy (<18 weeks), stratified by pre-pregnancy BMI status (normal weight [18.5-24.9 kg/m2]; overweight [25.0-29.9 kg/m2], obese [=>30.0 kg/m2]) and randomized into one of 3 groups: Group A) NELIP (full intervention); Group B) Nutrition intervention given at study entry followed sequentially by the exercise intervention starting immediately after 24 week mid-way visit (N+E); or Group C) Exercise intervention started at study entry followed sequentially by the nutrition intervention starting immediately after 24 week mid-way visit (E+N). Infant sex, body weight, length, complications will be recorded at birth and the last known maternal body weight. Neonatal morphometrics will be assessed with diaper only (6 skinfold sites from umbilical, suprailiac, biceps, triceps, subscapular, and anterior thigh; circumferences from the head, chest, abdomen, hips, thigh, leg, arm, and arm, forearm, thigh and leg length measured to the nearest mm) and will be measured within 6-18 hours of delivery by a member of the research team visiting the woman either at hospital or home. Each maternal-infant pair will be asked to return to the lab at 2, 6 and 12 months post-delivery for follow-up and assessment of chronic disease risk.

Inclusion Criteria:

• single pregnancy (no twins);
• < 18 weeks, 0 days pregnant at time of entry to study;
• low-risk pregnancy, as determined by medical pre-screening via PARmed-X for Pregnancy by their health care provider;
• > 18 years of age;
• low physical activity defined as less than 3 intentional bouts of 30 minutes of moderately intense physical activity per week;
• non smokers.

Exclusion Criteria:

• multiple pregnancy (twins, etc);
• contraindication to exercise (includes chronic diseases such as cardiovascular diseases, thyroid diseases, uncontrolled Type 2 diabetes, peripheral vascular disease, hypertension);
• > 18 weeks, 0 days pregnant at time of entrance to study;
• <18 years of age;
• high physical activity defined as more than 3 intentional bouts of 30 minutes of moderately intense physical activity per week;
• smokers.