Background: We have previously demonstrated that maternal body build and lifestyle factors predict neonatal bone mineral accrual. However, the paternal determinants of neonatal bone mass are not known. In this study we explored the relationship between a father's bone mass and that of his offspring.

Methods: 278 pregnancies (142 male and 136 female neonates) were recruited from the Southampton Women's Survey, a unique, well-established cohort of women, aged 20–34 years, who had been assessed before and during pregnancy. The neonates and their fathers underwent whole body DXA within 2 weeks of birth using a Lunar DPX and Hologic Discovery instrument respectively; correlation and regression methods were used to explore the parental determinants of neonatal bone mass.

Results: After adjusting the paternal DXA indices for father's age, and the neonatal for baby's gestational age, sex and age at DXA scan, there were highly significant positive associations between baby's whole body bone area (BA), bone mineral content (BMC), and bone mineral density (BMD) and the corresponding indices in the father (p=0.003, 0.0002, 0.046 respectively) among female infants. These relationships were independent of maternal height and fat stores. The associations for male infants with paternal DXA indices did not achieve statistical significance.

Conclusions: Father's skeletal size predicts skeletal size more strongly in female than male offspring, independently of the mother's body build. These data point towards the importance of considering paternal genotype in studies exploring the developmental origins of osteoporotic fracture, and raise intriguing mechanistic questions about the gender-specificity of influences on intrauterine bone mineral accrual.