title: Number of Children and Telomere Length in Women: A Prospective, Longitudinal Evaluation.
abstract: Life history theory (LHT) predicts a trade-off between reproductive effort and the pace of biological aging. Energy invested in reproduction is not available for tissue maintenance, thus having more offspring is expected to lead to accelerated senescence. Studies conducted in a variety of non-human species are consistent with this LHT prediction. Here we investigate the relationship between the number of surviving children born to a woman and telomere length (TL, a marker of cellular aging) over 13 years in a group of 75 Kaqchikel Mayan women. Contrary to LHT's prediction, women who had fewer children exhibited shorter TLs than those who had more children (p = 0.045) after controlling for TL at the onset of the 13-year study period. An "ultimate" explanation for this apparently protective effect of having more children may lay with human's cooperative-breeding strategy. In a number of socio-economic and cultural contexts, having more chilren appears to be linked to an increase in social support for mothers (e.g., allomaternal care). Higher social support, has been argued to reduce the costs of further reproduction. Lower reproductive costs may make more metabolic energy available for tissue maintenance, resulting in a slower pace of cellular aging. At a "proximate" level, mechanisms involved may include the actions of the gonadal steroid estradiol, which increases dramatically during pregnancy. Estradiol is known to protect TL from the effects of oxidative stress as well as increase telomerase activity, an enzyme that maintains TL. Future research should explore the potential role of social support as well as that of estradiol and other potential biological pathways in the trade-offs between reproductive effort and the pace of cellular aging within and among human as well as in non-human populations.
authors.affiliation: Maternal and Child Health Laboratory, Faculty of Health Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, V5A 1S6, Canada.
authors.forename: Cindy K
authors.initials: CK
authors.lastname: Barha
authors.affiliation: Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.|Child and Family Research Institute, Vancouver, British Columbia, V6T 1Z4, Canada.
authors.forename: Courtney W
authors.initials: CW
authors.lastname: Hanna
authors.affiliation: Maternal and Child Health Laboratory, Faculty of Health Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, V5A 1S6, Canada.|Human Evolutionary Studies Program, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, V5A 1S6, Canada.
authors.forename: Katrina G
authors.initials: KG
authors.lastname: Salvante
authors.affiliation: Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.|Child and Family Research Institute, Vancouver, British Columbia, V6T 1Z4, Canada.
authors.forename: Samantha L
authors.initials: SL
authors.lastname: Wilson
authors.affiliation: Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.|Child and Family Research Institute, Vancouver, British Columbia, V6T 1Z4, Canada.
authors.forename: Wendy P
authors.initials: WP
authors.lastname: Robinson
authors.affiliation: Statistics and Actuarial Science, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, V5A 1S6, Canada.
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Altman
authors.affiliation: Maternal and Child Health Laboratory, Faculty of Health Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, V5A 1S6, Canada.|Human Evolutionary Studies Program, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, V5A 1S6, Canada.
authors.forename: Pablo A
authors.initials: PA
authors.lastname: Nepomnaschy
mesh_terms: D000328:Adult; D000375:Aging / Q000378:metabolism*; D016922:Cellular Senescence / Q000235:genetics*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008875:Middle Aged; D018384:Oxidative Stress / Q000235:genetics; D010298:Parity / Q000502:physiology*; D011247:Pregnancy; D011446:Prospective Studies; D016615:Telomere / Q000378:metabolism*