Wednesday, November 21, 2007

Worrisome large increases in paternal age in last 25 or so years

Genetic quality of sperm
Although increasing maternal age has long been known to be associated with increased
incidence of birth defects, the age of the male as been seen as irrelevant. New data show
what we should have suspected all along: the age of the male does matter and the genetic
quality of sperm does decline with age. Specifically, a 2004 study by Malaspina et al.,
found that older men are at higher risk of fathering a child with schizophrenia. In fact
men older than forty were more than twice as likely to have a child with schizophrenia as
men in their twenties. A 2003 study (Fisch et al.) found a similar influence of paternal
age on the risk of having a child with Down Syndrome. Paternal age was a factor in half
the cases of Down Syndrome when the maternal age was over 35. And a 2002 study by
Rochebrochard and Thonneau of the rate of miscarriages found similar increased risks
with rising paternal age when maternal age was older than 35. These and other studies
clearly show that when the mother and father are both over the age of 35 years, there is a
markedly increased risk of both genetic abnormalities and miscarriage. The father’s
contribution to these events is increased with increasing age, similar to women. As noted
above, these facts are worrisome in light of the large increases in maternal and paternal
age over the past 25 years.



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