Background: Most previous studies on the effect of paternal age have focused on the association of advanced paternal age with congenital anomalies. The objective of this study was to determine whether paternal age is associated with the risk of adverse birth outcomes, independent of maternal confounders.
Methods: We carried out a retrospective cohort study of 2 614 966 live singletons born to married, nulliparous women aged 20-29 years between 1995 and 2000 in the USA. Multiple logistic regressions were applied to estimate the independent effect of paternal age on adverse birth outcomes.
Results: Compared with infants born to fathers aged 20-29 years, infants fathered by teenagers (<20 years old) had an increased risk of preterm birth [odds ratio (OR) = 1.15, 95% confidence interval (CI): 1.10, 1.20], low birth weight (OR = 1.13, 95% CI: 1.08, 1.19), small-for-gestational-age births (OR = 1.17, 95% CI: 1.13, 1.22), low Apgar score (OR = 1.13, 95% CI: 1.01, 1.27), neonatal mortality (OR = 1.22, 95% CI: 1.01, 1.49) and post-neonatal mortality (OR = 1.41, 95% CI: 1.09, 1.82). Advanced paternal age (> or =40 years) was not associated with the risk of adverse birth outcomes.
Conclusions: Teenage fathers carry an increased risk of adverse birth outcomes that is independent of maternal confounders, whereas advanced paternal age is not an independent risk factor for adverse birth outcomes.