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Does Having Children Extend Life Span? A Genealogical Study of Parity and Longevity in the Amish

¹ Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, Baltimore.
² Department of Medicine, University of Maryland School of Medicine, Baltimore.
³ Information Engineering Branch and ⁴ Computational Biology Branch, National Center for Biotechnology Information, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland.
⁵ Department of Internal Medicine, Division of Medical Genetics, University of Texas at Houston.
⁶ Geriatrics Research and Education Clinical Center, Veterans Administration Hospital Medical Center, Baltimore, Maryland.

Address correspondence to Braxton D. Mitchell, PhD, University of Maryland School of Medicine, Division of Endocrinology, Diabetes, and Nutrition, 660 W. Redwood St., Room 492, Baltimore, MD 21201. E-mail: bmitchel{at}medicine.umaryland.edu

Background. The relationship between parity and life span is uncertain, with evidence of both positive and negative relationships being reported previously. We evaluated this issue by using genealogical data from an Old Order Amish community in Lancaster, Pennsylvania, a population characterized by large nuclear families, homogeneous lifestyle, and extensive genealogical records.

Methods. The analysis was restricted to the set of 2015 individuals who had children, were born between 1749 and 1912, and survived until at least age 50 years. Pedigree structures and birth and death dates were extracted from Amish genealogies, and the relationship between parity and longevity was examined using a variance component framework.

Results. Life span of fathers increased in linear fashion with increasing number of children (0.23 years per additional child; p =.01), while life span of mothers increased linearly up to 14 children (0.32 years per additional child; p =.004) but decreased with each additional child beyond 14 (p =.0004). Among women, but not men, a later age at last birth was associated with longer life span (p =.001). Adjusting for age at last birth obliterated the correlation between maternal life span and number of children, except among mothers with ultrahigh (>14 children) parity.

Conclusions. We conclude that high parity among men and later menopause among women may be markers for increased life span. Understanding the biological and/or social factors mediating these relationships may provide insights into mechanisms underlying successful aging.