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Perls et al. report a significant fourfold excess of births in middle age (N=19 women age 40 or older) among 78 female centenarians when compared with a group of 54 women in the same birth cohort (born in Massachusetts in 1896) who survived only to the age of 73. We re-examined this question using data derived from a large case-control of postmenopausal breast cancer in Massachusetts, New Hampshire and Wisconsin2. In that study, women provided detailed information on family history, including maternal and sibling dates of birth, survival status and dates of death, and data on socioeconomic status, race, religion and maternal smoking.

We identified the 3,578 mothers of control women (subjects without breast cancer) who survived at least to the age of 70 (70% were deceased at the time of the daughter's interview). All were born between 1867 and 1923 (median, 1900), and 552 (15.4%) had given birth after their fourth decade. In an unadjusted model, the mortality rate from all causes was slightly increased (by 11%) in association with late childbirth (rate ratio, 1.11; 95% confidence interval, 1.01-1.23; P=0.04). However, after adjusting for smoking and socioeconomic status, this excess disappeared (rate ratio, 1.01; 95% confidence interval, 0.90-1.13; P=0.83). Only 27 women lived to age 100 or beyond. Among the 1,167 women born in 1896 (the birth year of women in ref. 1) or earlier, the proportion bearing children after age 40 was higher in the 352 women who died between the ages of 70 and 79 (31%) than in the 322 women who survived to age 90 (24%). Thus, in this population of elderly parous women, all of whom had given birth to at least one child, we find no evidence that childbearing in ‘middle age’ is a reliable marker of longevity.