The relationship between paternal age and early mortality of triplets in the United States

We sought to determine the impact of advanced paternal age on the birth outcomes of triplets in a retrospective cohort study on 15,156 triplets born in the United States from 1995 to 1997. The study group comprised fathers aged > or = 40 years. Two control groups consisting of mature (30 to 39 years) and younger (20 to 29 years) fathers were constructed for comparison of main end points. We applied the generalized estimating equation framework to obtain relative risk estimates after capturing the effect of sibling correlations within triplet clusters. Stillbirths were 35% and 26% higher among triplets of mature and older men, respectively, whereas neonatal mortality was 28% and 23% lower among infants of mature and older fathers, respectively, using younger fathers as the referent category. Although only the relative risk for neonatal mortality comparing triplets of mature and younger fathers was statistically significant, these results constitute high indices that represent an important burden of excess early mortality at the population level. Our findings demonstrate a "shifting phenomenon" whereby a higher level of intrauterine demise was compensated by a higher rate of extrauterine survival among triplets born to older fathers.