Paternal age at birth and the risk of obesity in young adulthood: a register-based birth cohort study of Norwegian males.
OBJECTIVE
The aim of this study was to determine the relationship between paternal age at birth and the risk of obesity in young adulthood.


METHODS
Data from the medical birth register of Norway were linked with register data from the Norwegian National Conscript Service and the national statistics agency, Statistics Norway. This study used the data on 346,609 registered males who were born at term in single birth without physical anomalies during 1967-1984 and who were examined at the time of the mandatory military conscription (age 18-20 years). The relationship between paternal age at birth and the occurrence of obesity (body mass index (BMI) ≥ 30.0 kg/m(2) ) at conscription was examined using a multinomial logistic regression analysis with BMI < 25.0 kg/m(2) as the reference outcome category.


RESULTS
The relative risk of obesity at conscription increased linearly with increasing paternal age at birth but did not increase (P = 0.52) with maternal age at birth. Men born when their fathers were 50 years or older had a 55% (95% confidence interval (CI): 14%, 110%) higher relative risk of obesity than men born when their fathers were younger than 20 years of age, after adjustment for age at conscription, birth order, birth year, maternal age at birth, the mother's total number of children, and maternal and paternal education levels.


CONCLUSIONS
The risk of obesity in young Norwegian men increases with advancing paternal age at birth but does not increase with advancing maternal age at birth.
Division of Mental Health, Norwegian Institute of Public Health, Nydalen, 0403 Oslo, Norway. w-bjarer@online.no
Willy
W
Eriksen
Jon M
JM
Sundet
Kristian
K
Tambs
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001722:Birth Order; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008423:Maternal Age; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D009765:Obesity / Q000453:epidemiology*; D010298:Parity; D010331:Paternal Age; D012042:Registries; D012307:Risk Factors; D055815:Young Adult