Hurley EG, et al. – The purpose of this study is to ascertain the impact of paternal age on perinatal outcomes, and to evaluate whether this impact varies between pregnancies achieved spontaneously and those achieved with assisted reproductive technology (ART). Older paternal age does not seem to pose an independent risk of adverse perinatal outcomes, either in pregnancies achieved with or without ART. However, small impact sizes, for example, very small risk increases or decreases may not be detectable despite the large sample size in this study of over 830,000 births.