Influence of maternal and paternal birthweight on offspring birthweight - a population-based intergenerational study

The correlation between infant birthweight and parental birthweight has received substantial interest. However, fewer studies including the birthweight of the father have had access to large sets of population-based data. The objective of this study is to examine the influence of maternal and paternal birthweight on the birthweight of the offspring in the context of other birthweight determinants, with a special focus on the contribution of paternal birthweight.

The data used were retrieved from the Swedish Population Register, Medical Birth Register and Multi-Generation Register. Full-term, singleton births were included and linked through personal ID numbers given to every resident at birth, forming 137 538 mother-father-child units with valid birthweights. The analyses were made through linear regression models.

The positive association for both maternal and paternal birthweight remained after introducing other determinants in the model, yielding a difference in offspring birthweight by 164 g [95% confidence interval 159, 170] and 149 g [95% confidence interval 145, 154] for every 1000 g rise in birthweight of the mother and father respectively. Maternal birthweight explained 6% of the variance in birthweight, whereas paternal birthweight explained 3%. There was no difference when analyses were stratified according to gender.

These results suggest that maternal and paternal birthweight remain relevant for infant birthweight, even after consideration of other determinants of birthweight.