Associations Between Paternal Pre‐Conceptional Body Mass Index and Lifestyle Factors and Offspring Weight Development

Background Evidence suggests that pre‐conceptional paternal factors, including BMI and diet, may influence offspring development. Objectives We examined the associations between paternal BMI, dietary protein intake, glycemic index (GI), smoking and alcohol consumption and offspring development during the first 5 years of life. Methods This secondary analysis of an RCT included 162 father‐child pairs from pregnancies among women with pre‐pregnancy overweight or obesity. Paternal characteristics were reported at gestational week 15, reflecting the preceding 3 months. Offspring anthropometry was measured at birth, 6 and 18 months, 3 and 5 years. Associations were examined using linear mixed models and linear regression models. Results No consistent associations were found between paternal characteristics and offspring outcomes from birth to 3 years. At age 5, higher paternal BMI was associated with higher offspring BMI z ‐score ( β = 0.07 (CI: 0.03; 0.10)), fat mass index ( β = 0.07 kg/m 2 (CI: 0.02; 0.12)) and fat‐free mass index ( β = 0.05 kg/m 2 (CI: 0.01; 0.08)). Lower paternal protein intake was associated with higher offspring BMI z ‐score ( β = 0.54 (CI: 0.07; 1.01)) and fat‐free mass index ( β = 0.60 kg/m 2 (CI: 0.13; 1.07)), while moderately higher protein intake was associated with higher waist‐to‐height ratio ( β = 0.03 (CI: 3.00 × 10 −3 ; 0.05)). Higher paternal GI was associated with lower offspring BMI z ‐score ( β = −0.04 (CI: −0.08; −2.14−10 −3 )) at age 5. Smoking and alcohol were not associated with offspring outcomes. Conclusion Paternal BMI was associated with offspring outcomes at age 5 years, while findings for paternal dietary factors were less consistent.