Background: Advanced paternal age has been linked to early preterm delivery (before 32 weeks).
Methods: We analyzed live births from white, non-Hispanic primiparas recorded in U.S. birth certificates from 1995 to 2000 (excluding California). We examined 2,509,012 pregnancies of married women 20 to 34 years old, excluding unmarried women due to the high fraction of missing data on father's age. We defined the outcome according to the clinical estimate of gestation after excluding unlikely birth weights, because the estimate based on last menstrual period is particularly prone to errors at early gestations.
Results: Older paternal age was not associated with increased risk of early preterm delivery. The highest estimated odds ratio among fathers 50 years or older was 1.3 (95% confidence interval = 0.6-2.8) among women 20 to 24 years old.
Conclusions: These U.S. data do not support an association between advanced paternal age and delivery before 32 weeks.