Associations of parental pre-pregnancy BMI with cardiometabolic risk in offspring conceived via assisted reproductive technology: a retrospective cohort study

Background Parental pre-pregnancy adiposity may influence offspring cardiometabolic health, but the independent and joint contributions of maternal and paternal body mass index (BMI) remain uncertain, particularly among children conceived through assisted reproductive technology (ART). We examined sex-specific associations of parental pre-pregnancy BMI with cardiometabolic profiles in ART-conceived children. Methods This retrospective cohort study included 2,989 singleton children conceived through ART and assessed at 3–6 years of age. Parental pre-pregnancy BMI was obtained from prospectively recorded clinical records. Offspring outcomes included BMI, blood pressure, fasting glucose, lipid profiles, the triglyceride-glucose body mass index (TyG-BMI), and the metabolic score for insulin resistance (METS-IR). Linear and logistic regression models, sex-stratified analyses, parental overweight/obesity combination analyses, and mediation analyses were performed. Results Higher maternal and paternal pre-pregnancy BMI were each associated with higher offspring BMI and insulin resistance indices. Maternal BMI showed stronger associations with offspring BMI than paternal BMI in boys (β = 0.121 vs 0.055) and girls (β = 0.090 vs 0.056; all P < 0.001). Compared with children whose parents were not overweight/obese, the largest increases in TyG-BMI were observed when both parents had overweight/obesity: 5.918 (95% CI 2.820–9.016) in girls and 8.805 (95% CI 5.840–11.770) in boys (both P < 0.001). Similar patterns were observed for METS-IR, with corresponding increases of 1.081 (95% CI 0.513–1.648) in girls and 1.609 (95% CI 1.077–2.141) in boys. Mediation analyses indicated that child BMI accounted for most of the mediated association between parental BMI and offspring insulin resistance indices, whereas birthweight contributed less. Conclusions Both maternal and paternal pre-pregnancy BMI were associated with cardiometabolic profiles in ART-conceived children, and children with overweight/obesity in both parents showed the greatest elevations in insulin resistance indices. These findings support preconception weight management for both parents and early monitoring of offspring weight as potential targets for cardiometabolic risk reduction.