Between 1988 and 2010, the average donor age rose by almost 10 years, and the proportion of donors who were over age 50 grew from 16 percent to 38 percent.

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The donor's age is a factor because if he dies before the end of the GRAT term, the stock bounces back into his estate.

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The ideal age for a donor, however, is 18 to 25 years of age, thus making college campuses an ideal spot to recruit potential donors.

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So with donor eggs, could a woman get pregnant at, say, age 80?

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Five years ago the government lifted the anonymity granted to donors, so that now any offspring conceived by the donor method, are able to trace their biological parents when they get to the age of 18.

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But legally requiring fertility clinics to disclose to donors at age 18, at minimum, anonymized medical information and actual identifying information unless the donor opts-out ignores both how fertility treatments are provided in the US and the fact that parents are routinely given all that information during the donor selection process.

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Of the millions of people with sickle-cell disease in the world, only some 300 have received a bone marrow transplant because of age (doctors won't perform the procedure on patients 16 years and older) and donor-matching problems.

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