Chasidut for Shabbat 311:14

‎Genesis 23,1. “The years of Sarah’s life were one hundred years, ‎etc.;” I believe, G’d willing, that I have understood the reason ‎why Sarah is the only woman in the Bible of whose age at the ‎time of her death we have been told. The Talmud Nedarim ‎‎64, in referring to Rachel’s outburst (Genesis 30,1) that unless her ‎husband Yaakov would give her children she considered herself as ‎‎“dead,” is quoted by Rashi on that verse saying that seeing ‎that a woman’s primary task in life is to mother children, any ‎woman who has not given birth to a live child is considered as ‎dead. We also know from Shabbat 156, that when G’d took ‎Avraham outside (Genesis 15,5) that He showed him that ‎according to the constellation of the stars, Sarai was not slated to ‎give birth to children. This ‎מזל‎, astrological prognosis of her life, ‎could be changed only due to merits she would acquire during the ‎years to come. She did indeed acquire such merits, as our sages ‎conclude from a comment they made in Shir Hashirim ‎Rabbah, 2,32 where the phenomenon of all the matriarchs ‎originally being barren is discussed. Among a variety of answers ‎offered there, one is that G’d was desirous of listening to their ‎praying to Him to be granted children, just as He is desirous of ‎listening to the prayers of the righteous, generally. In other ‎words, Sarah, (after a name change) both due to her merits and ‎her supplications, was “lifted” out of the limitations predicted for ‎her by a zodiac sign she had been born under, so that she could ‎conceive. When the Torah refers to her “life” as being 127 years ‎long, this means nothing less than that she had spent all these ‎years accumulating merits for the good deeds she performed. ‎Expressed somewhat differently, the Torah states that it was ‎Sarah, who with her good deeds gave “life” to her years.‎