Relationship of paternal factors to birth weight.

OBJECTIVE: To investigate the relationship between paternal characteristics and birth weight.

STUDY DESIGN: A total of 241 gravidas with uncomplicated, singleton, term pregnancies were studied. Maternal demographic and pregnancy-specific characteristics were used to calculate the expected birth weight for each fetus using a previously validated birth weight prediction equation. The additional independent predictive value of 4 paternal variables was assessed using multiple regression.

RESULTS: Before adjustment for other variables, paternal height and weight significantly correlated with birth weight, but paternal age and body mass index did not. After controlling for maternal and pregnancy-specific factors that are known to influence fetal weight, only paternal height was significant as a predictive variable. The proportion of variance in birth weight that could be independently explained by paternal height was 2%. A 10-g gain in fetal weight was associated with each centimeter of increase in paternal height (P < .02). Using the resulting combination equation that included paternal height as a variable, 31% of the variance in term birth weight could be explained, and birth weights could be accurately predicted to within +/- 8.3% (+/- 288 g). Fathers with heights 2 SD above and below the mean had the term birth weight of their offspring increased and diminished by 125 g, respectively.

CONCLUSION: Paternal height explains an independent portion of the variance in term birth weight among normal newborns of up to 250 g that cannot be explained by other maternal or pregnancy-specific factors. Paternal age, weight and body mass index do not independently influence birth weight.