Maternal preconception obesity and adverse gestational metabolic health increase the risk of childhood obesity in offspring. A group of investigators from Université de Sherbrooke therefore developed a lifestyle intervention starting during preconception in women with obesity and infertility, which was evaluated with the Obesity-Fertility randomized controlled trial (RCT). The present study will assess children who were born in the Obesity-Fertility RCT and are now aged 6-10 years old. The objective of this study is to evaluate the effect of a lifestyle intervention during preconception and pregnancy on adiposity and cardiometabolic parameters in offspring compared to those born to mothers who did not have access to the lifestyle intervention. The hypothesis being that, at the age of 6-10 years old, children born to mothers who were in the intervention group have more favorable measurements of body composition and certain metabolic and/or inflammatory blood markers than those born to control mothers.

Participants in the Obesity-Fertility RCT were women with obesity and infertility recruited at the Centre hospitalier universitaire de Sherbrooke (CHUS) fertility clinic. They were randomly allocated to the control group, which followed standard care, or to the intervention group, which received a lifestyle intervention alone for 6 months, and then in combination with fertility treatments. Those who have given birth to a single child will be invited to participate in this follow-up study with their child. During the research visit, medical history, anthropometry, body composition, lifestyle, physical fitness level, and blood or saliva markers of cardiometabolic health will be assessed for both mothers and children.

This study will provide new evidence on the impact of targeting lifestyle habits during preconception on the health of children and their mothers 6-10 years later; and the potential of such interventions to counteract the intergenerational transmission of obesity.

INTRODUCTION: Maternal preconception obesity and adverse gestational metabolic health increase the risk of childhood obesity in offspring. A group of investigators from Université de Sherbrooke therefore developed a lifestyle intervention starting during preconception in women with obesity and infertility, which was evaluated with the Obesity-Fertility randomized controlled trial (RCT) registered at ClinicalTrials.gov (NCT01483612). The present study will assess children who were born in the Obesity-Fertility RCT and are now aged 6-10 years old. The objective of this study is to evaluate the effect of a lifestyle intervention during preconception and pregnancy on adiposity and cardiometabolic parameters in offspring compared to those born to mothers who did not have access to the lifestyle intervention.

METHODS AND ANALYSIS: Participants in the Obesity-Fertility RCT were women with obesity and infertility recruited at the CHUS fertility clinic between January 2012 and August 2018. They were randomly allocated to the control group, which followed standard care, or to the intervention group, which received a lifestyle intervention alone for 6 months, and then in combination with fertility treatments. Those who have given birth to a single child will be invited to participate in this follow-up study with their child. This study will take place from October 2023 to September 2024, when the child will be 6-10 years old. During the research visit, medical history, anthropometry, body composition, lifestyle, physical fitness level, and blood or saliva markers of cardiometabolic health will be assessed for both mothers and children. Of the 130 women who participated in the Obesity-Fertility RCT, 53 mother-child dyads are potentially eligible for this follow-up study. Comparisons between groups will be performed using appropriate unpaired tests and adjusted for potential confounders using multiple regression models.

ETHICS AND DISSEMINATION: The study has been approved by the Institutional Research Ethics Review Boards of the CHUS. The results will be widely disseminated to the scientific community as well as to relevant health professionals and the general public.

IMPACT: This study will provide new evidence on the impact of targeting lifestyle habits during preconception on the health of children and their mothers 6-10 years later; and the potential of such interventions to counteract the intergenerational transmission of obesity.

Inclusion Criteria:

• Offsprings of women who were randomized in the Obesity-Fertility study known to have been conceived within 18 months following randomization of their mothers from a singleton pregnancy.

Exclusion Criteria:

• Children having a disease or taking a medication that has a major impact on weight, anthropometry, lifestyle habits or functional capacity (e.g., congenital heart disease, functional disability, severe asthma, regular use of glucocorticoids, etc.).

Children born from mothers who participated in the Obesity-Fertility study. Those mother were recruited between 2012 and 2018 at the fertility clinic of the Centre hospitalier universitaire de Sherbrooke. To be included in the study, they had to be aged between 18 and 40 years and living with infertility and obesity, or overweight if they had polycystic ovary syndrome (PCOS). Women were excluded if they had undergone or were planning bariatric surgery, or if natural conception was impossible or unlikely (such as both fallopian tubes blocked or severe male factor).