Obesity-fertility cohort study: protocol for the assessment of children aged 6-12 years and their mothers.

introductionMaternal preconception obesity and adverse gestational metabolic health increase the risk of childhood obesity in offspring, but the preconception period may be an opportune time to intervene, given the motivation of the mother and the epigenetic changes that may be beneficial for the gametes during this period. However, there is a lack of studies evaluating children born to women who have had a preconception intervention. Our group has therefore designed an ancillary study to assess children born to women enrolled in the obesity-fertility randomised controlled trial (RCT), who were 6-12 years of age, with the objective of evaluating the effect of a lifestyle intervention delivered during preconception and pregnancy on adiposity and cardiometabolic parameters in the offspring. This manuscript details the study protocol. METHODS AND ANALYSIS: This is an ancillary nested cohort study of the obesity-fertility RCT. Women with obesity and infertility were recruited at an academic fertility clinic and randomised to the control group, which followed usual care, or to the intervention group, which received a lifestyle intervention alone for the first 6 months and then in combination with fertility treatments for up to 18 months or until the end of pregnancy. Those who have given birth to a single child are invited to participate in this follow-up study with their child aged 6-12 years. This study started in November 2023 and is expected to end in May 2025. The primary outcome is age-adjusted and sex-adjusted body mass index z-scores in children. Secondary outcomes are anthropometry, body composition, lifestyle, physical fitness level and blood or saliva markers of cardiometabolic health in both mothers and children. Of the 130 women who participated in the obesity-fertility RCT, 52 mother-child dyads (24 in the control group; 28 in the intervention group) were potentially eligible for this follow-up study. Comparisons between groups will be performed using unpaired tests and adjusted for potential confounders using multivariable regression models. This study will provide important new data on the impact of a preconception lifestyle intervention, maintained throughout pregnancy, on the health trajectory of children and mothers 6-12 years after delivery. ETHICS AND DISSEMINATION: The study has been approved by the institutional research ethics review boards of the TRIAL REGISTRATION NUMBER: ClinicalTrials.gov (NCT06402825).