In Canada, overweight and obesity are major public health concerns that affect nearly 45% of reproductive-age women. In pregnancy, overweight and excessive gestational weight gain are important risk factors for complications including gestational diabetes, hypertensive disorders of pregnancy, fetal macrosomia, and cesarean delivery. Women who are overweight in pregnancy and who gain excessive weight are also predisposed to subsequent obesity, and their offspring are predisposed to childhood obesity and metabolic syndrome. In light of the failure of pregnancy lifestyle interventions to improve pregnancy outcomes for overweight and obese women, earlier intervention is mandated. Preconception appears as a key period to prevent overweight and pregnancy complications.
The main objective of this study is to evaluate the impact of the Healthy for my Baby intervention on the diet quality of women in the preconception period, as measured with the Canadian Healthy Eating Index 2007 (C-HEI). Urinary profiling of dietary exposure biomarkers will be used as a secondary assessment of diet quality. Secondary outcomes for preconception include the effect of the intervention on the lifestyle habits and anthropometric measures of women and their partners.
In pregnancy, the main secondary objective is to evaluate the impact of the intervention on the pattern of gestational weight gain as defined by the 2009 Institute of Medicine recommendations. Other outcomes for pregnancy include the rates of gestational diabetes, hypertensive disorders of pregnancy, macrosomia, and cesarean delivery. The lifestyle habits of women and their partner and the anthropometric measures of their spouses will also be evaluated in pregnancy. Fertility outcomes will be reported as exploratory measures.
Eligible subjects are couples aged 18 to 40 years who wish to conceive within 12 months of trial inclusion, in which the female partner has a BMI ≥ 25 kg/m2. Exclusion criteria are insufficient knowledge of French or English, an anticipated move to another region, a personal history of infertility, type 1 or 2 diabetes mellitus, prior bariatric surgery, an eating disorder established by clinical diagnosis, medical contraindication to pregnancy, medical contraindication to physical activity, participation in another intensive lifestyle intervention, or a known or anticipated disease or surgery likely to cause an important weight loss. Multiple pregnancies will be excluded from the pregnancy follow-up to limit aberrant data.
Couples will be randomized in blocks to the intervention or control group in a 1:1 ratio with randomly selected block size. The intervention will include two sessions of motivational interviewing on healthy lifestyle in preconception, and two more sessions in pregnancy. As an adjunct to in-person meetings, couples will have access to a mobile phone application to self-monitor daily lifestyle smart goals. Participants in the control group will receive standard advice on lifestyle as provided by their usual care provider. To improve compliance with the study follow-up, participants in this group will have access to a simplified version of the mobile application that contains a fertility calendar and a research visit calendar.
Research visits will take place at study inclusion and every 3 months in preconception for up to 6 months. In pregnancy, study visits will take place in the first (6-8 weeks), second (24-26 weeks), and third (32-34 weeks) trimesters. The C-HEI will be measured at 0, 2, 4, and 6 months in preconception and every trimester in pregnancy with two web-based 24-hour dietary recalls. Urine samples will be collected at 0 and 2 months in preconception and at 24-26 weeks in pregnancy. Data on pregnancy and neonatal outcomes will be collected from medical files at the end of the trial.
A sample size of 54 women is required to detect a 10-point difference in the C-HEI score (maximal value 100) between the groups with an alpha value of 5%, 80% power, and a 13 points standard deviation. Sixty-eight women and their partners will be recruited to account for a 20% attrition rate.
The evolution of the C-HEI score with time in the preconception period will be compared between groups using a mixed linear model. Student's t-test will also be used to compare the average HEI-score between groups at 3, and 6-month follow-up. A statistical significance of 5% with Bonferroni correction for multiple comparisons will be used for the preconception primary outcome assessment. The concentration of 40 urinary metabolites will be compared between baseline, 2 months in preconception and 24-26 weeks of pregnancy using repeated measures ANOVA or Friedman test with a Bonferroni adjustment for multiple comparisons. The proportion of adequate gestational weight gain will be compared between groups with a Chi-squared test. Secondary outcomes will be assessed using Student's t-test, Wilcoxon test, Chi-squared test, or Fisher's exact test as appropriate. For all secondary outcomes statistical significance is set at 5%.
