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Older Sperm Causes Failed Pregnancy
Older men's sperm
can be the cause of increased spontaneous abortion in women.
The risk of miscarriage increases the older a man is.
Studies have shown older men have abnormalities in their sperm making their
children more susceptible to birth defects. Older men's sperm is associated
with their offspring having schizophrenia. The upper age limit on semen
donors has be set at 40 due to the increased risk of the older father's
genetic abnormalities.
Most likely these aren't the only problems found. Only recently have
researchers started looking at the problems associated with older fathers.
Some of them are destined to find other genetic problems.
Disorders linked to aging men's sperm begin to increase quickly around the
same time as women's risks increase, typically around age 33 to 35.
Men over the age of 50, typically were three times more likely to have sperm
that has some mutation as compared to a younger man of 30.
A study focused on spontaneous abortion of women dealt with many variables.
Things like maternal diabetes, female smoking habits
, history of abortions
and the socioeconomic status. The study found that with an aged male
partner, the rate of miscarriages increases. Men aged 35 or older were
shown to have three times as many miscarriages as men younger than 25
years of age.
So why do older men's sperm
contribute to miscarriages?
Men make a lot of sperm from puberty to death, around 1500 per second.
All of these are made by cells dividing.
When cells divide, each needs to copy all of the 3 million letters in its DNA.
Occasional mistakes happen resulting in genetic problems
.
So as a man ages, his sperm more often will carry more genetic mutations
than a younger man's. After many years, 20 or 30, of dividing, the sperm's
DNA starts building up genetic mistakes. When a man is younger his damaged
sperm tends to kill themselves. Older men's sperm tends to not kill
themselves when they are damaged.
This tells us that as men get older, sperm develops various changes in its
DNA which in turn can be passed to the offspring with various genetic
problems.
The mother's age was independent of the study on men's age.
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