Reproductive longevity and increased life expectancy.
BACKGROUND
Female life expectancy in developed countries has increased by 30 years in the twentieth century.


OBJECTIVE
To determine if there has been an increase in reproductive longevity.


METHODS
We analysed age-specific fertility data from birth statistics for the USA, Canada, Japan, France, Sweden, the UK and Australia.


RESULTS
Since 1940, birth rates for women aged 35 and over have declined. Among women aged 50 years and older, there has been no increase in births. Fertility rates in 1990 were 0.0 to 0.044 per 1000 women, with total numbers ranging from 0 to 60 births.


CONCLUSIONS
The fertile years have not been prolonged in the cohort of women whose life expectancy has increased so dramatically this century. This suggests that reproductive senescence is tightly controlled and not extended by factors that enhance female longevity. Other physiological mechanisms may also be fixed within narrow age limits.
Brody
J A
JA
Department of Epidemiology and Biostatistics, School of Public Health, University of Illinois at Chicago, 60612-7260, USA. BrodyJ@uic.edu
Grant
M D
MD
Frateschi
L J
LJ
Miller
S C
SC
Zhang
H
H
D000328:Adult; D000368:Aged; D001723:Birth Rate / Q000639:trends*; D015331:Cohort Studies; D003431:Cross-Cultural Comparison; D005260:Female; D006801:Humans; D008017:Life Expectancy / Q000639:trends*; D008593:Menopause; D008875:Middle Aged