A new study reveals that women who give birth to their first child late in their lives are more likely to live to an unusually old age.
In the nested case-control 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.
It was also 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.
NAMS Executive Director, Margery Gass, MD said that while this documented relationship was noteworthy, what was more meaningful was 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.
The study is published online in Menopause, the journal of The North American Menopause Society (NAMS).