Parental Age Effects on Offspring Telomere Length Across Vertebrates: A Meta-Analysis

Telomeres shorten with advancing age in numerous species, and shorter telomeres are linked to increased mortality risk. While parental age at conception can influence offspring telomere length, the magnitude and direction of this effect differ across studies, species, and parental sexes. To understand how parental age influences offspring telomere length across vertebrates, we conducted a systematic review and meta-analysis to examine the effects of paternal and maternal age at conception on offspring telomere length, incorporating 99 effect sizes from 30 human studies and 49 effect sizes from 12 non-human vertebrate studies. There was a positive overall parental age effect on offspring telomere length within human studies, while no effect was found in non-human vertebrate studies after adjusting for study, estimate, and phylogenetic effects. Considerable heterogeneity was attributed mainly to between-study variance in human studies and to phylogeny in non-human studies. Parental age effect estimates were correlated with the laboratory methods used for measuring telomere length in all studies. In human studies, the interaction between parental and offspring sex affected the parental age effect estimates, and estimates derived from leukocytes were less positive than those from other cells. In non-human vertebrates, parental age effects were less negative when the parents' identity was controlled for in the study. Publication biases suggest overestimation of the parental age effect in human studies. We recommend that future research be conducted on a broader range of taxa, test for within-parent effects, and follow standardised reporting practices to enhance data comparability.