Women who had their children later in life will be happy to learn that a new study suggests an association between older maternal age at birth of the last child and greater odds for surviving to an unusually old age. That's according to a nested case-control study published online today in Menopause, the journal of The North American Menopause Society (NAMS).
In this study which used Long Life Family Study data, 311 women who survived past the oldest fifth percentile of survival (according to birth cohort-matched life tables) were identified as cases, along with 151 women who died at ages younger than the top fifth percentile of survival who were identified as controls. Looking at the cases of all 462 women, the study found a significant association for older maternal age, whereby women who had their last child beyond age 33 years had twice the odds for survival to the top fifth percentile of survival for their birth cohorts compared with women who had their last child by age 29 years. More specifically, women between the ages of 33 and 37 having their last child had an odds ratio of 2.08. The odds ratio for older women was 1.92.
Several previous studies had observed a similar association. For example, an analysis of New England Centenarian Study cohort data revealed that women who gave birth to a child after age 40 years had four times greater odds for being a centenarian compared with women from the same birth cohort who had their last child at a younger age.
In this latest study, it was observed that having more children (identified as three or more) tempered the association between increased maternal age and later survival. Mortality was not assessed for women who had no children.
According to the authors, the fact that numerous studies have documented the same relationship between older maternal age at birth and exceptional survival provides evidence for sustained reproductive fitness, with age as a selective force for genetic variants conducive to longer life.
"While this documented relationship is noteworthy, what is more meaningful is that these findings support the need to conduct additional studies that identify the various genetic influences on reproductive fitness, as these could also influence the rate of aging and a woman's susceptibility to age-related diseases," says NAMS Executive Director Margery Gass, MD.
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