Drinking Alcohol During Pregnancy May Damage Semen Quality in Sons
Posted by Marc Sklar at 7/13/2010 
Categories: HEALTH, Alcohol During Pregnancy, fetal alcohol, pregnancy, pregnancy health, Alcohol
Tags: pregnancy Alcohol During Pregnancy health fetal alcohol pregnancy health Alcohol
Categories: HEALTH, Alcohol During Pregnancy, fetal alcohol, pregnancy, pregnancy health, Alcohol
Tags: pregnancy Alcohol During Pregnancy health fetal alcohol pregnancy health Alcohol
ScienceDaily (June 29, 2010)
Mothers who drink alcohol while they are pregnant may be damaging the
fertility of their future sons, according to new research being presented at
the 26th annual meeting of the European Society of Human Reproduction
and Embryology in Rome.
Doctors in Denmark found that if mothers had drunk 4.5 or more drinks a week
while pregnant, then the sperm concentration of their sons, measured about
20 years later, was a third lower in comparison to men who were not exposed
to alcohol while in the womb. A drink was measured as 12 grams of alcohol,
which is the equivalent to one 330 ml beer, one small (120 ml) glass of wine
or one glass of spirits (40 ml).
Dr Cecilia Ramlau-Hansen, senior researcher at the Department of
Occupational Medicine, Aarhus University Hospital (Denmark) and clinical
associate professor at the Department of Epidemiology, Institute of Public
Health, University of Aarhus, told a news briefing: "Our study shows that
there is an association between drinking a moderate amount of alcohol (about
four to five drinks a week) during pregnancy and lower sperm concentrations
in sons. However, because this is an observational study we cannot say for
certain that the alcohol causes the lower sperm concentrations. It is
possible that drinking alcohol during pregnancy has a harmful effect on the
foetal semen-producing tissue in the testes -- and thereby on semen quality
in later life -- but our study is the first of its kind, and more research
within this area is needed before any causal link can be established or safe
drinking limits proposed."
Dr Ramlau-Hansen and her colleagues studied 347 sons of 11,980 women with
singleton pregnancies who were recruited to the Danish "Healthy habits for
two" study between 1984-1987. Around the 36th week of pregnancy the mothers
answered a questionnaire on lifestyles and health. The sons were followed up
between 2005-2006, when they were aged between 18-21, and semen and blood
samples were collected and analysed.
The researchers divided the sons into four groups, ranging from those who
were least exposed to alcohol (their mothers had drunk less than one drink a
week) -- and this was the reference group against which the other groups
were measured -- to those whose mothers drank 1-1.5 drinks a week, 2-4
drinks a week, or 4.5 or more drinks per week.
They found that sons of mothers drinking 4.5 or more alcoholic drinks a week
had average sperm concentrations of 25 million per millilitre, while the
sons who were least exposed to alcohol had sperm concentrations of 40
million/ml. After adjusting for various confounding factors, they found the
sons in the group most exposed to alcohol had an average sperm concentration
that was approximately 32% lower than that in the least exposed group.
The World Health Organization defines a "normal" level of sperm
concentration as being approximately 20 million/ml or more. Dr Ramlau-Hansen
said: "The reduced sperm concentrations in the most exposed men are rather
close to the lower end of the WHO's normal range for fertility. The
probability of conception increases with increased sperm concentration up to
40 million/ml and so it is possible that the most exposed men could be less
fertile than the least exposed."
She found that semen volume and total sperm count (which also affect a man's
fertility) were associated with prenatal alcohol exposure; these were
highest in sons whose mothers drank 1-1.5 drinks a week. The researchers
could find no association between alcohol exposure and the movement and
shape of the sperm or with any reproductive hormones such as testosterone.
Dr Ramlau-Hansen said: "Our finding that sons prenatally exposed to 1-1.5
drinks per week had higher semen volume and total sperm count compared to
the least exposed group is not surprising and is quite a common finding when
studying alcohol. It could indicate that small amounts of alcohol have a
beneficial effect (for example, on the semen-producing tissue in the foetal
testes), but, in fact, we believe this result may be biased by the
characteristics of the women drinking small amounts of alcohol during
pregnancy or by inaccurate reporting of alcohol consumption. Therefore, it
is not possible to draw a firm conclusion from this result."
The researchers also investigated whether fathers' alcohol consumption had
any effect. "We investigated the association between fathers' total alcohol
intake and semen quality in the sons and found that paternal alcohol was not
associated with semen volume or sperm concentration. This finding suggests
that the observed associations between maternal alcohol consumption and
sons' semen quality are not confounded by lifestyle factors that are shared
by a couple, such as smoking," said Dr Ramlau-Hansen.
She concluded: "If further research shows that maternal alcohol consumption
is a cause of reduced semen concentration in male offspring, then we are a
bit closer to an explanation of why semen quality may have decreased during
the last decades and why it differs between populations. If exposure to
alcohol in foetal life causes poor semen quality in adult life, we would
expect that populations with many pregnant women drinking, possibly heavily,
in pregnancy would have lower fertility in comparison with populations of
where pregnant women do not drink."
Doctors in Denmark found that if mothers had drunk 4.5 or more drinks a week
while pregnant, then the sperm concentration of their sons, measured about
20 years later, was a third lower in comparison to men who were not exposed
to alcohol while in the womb. A drink was measured as 12 grams of alcohol,
which is the equivalent to one 330 ml beer, one small (120 ml) glass of wine
or one glass of spirits (40 ml).
Dr Cecilia Ramlau-Hansen, senior researcher at the Department of
Occupational Medicine, Aarhus University Hospital (Denmark) and clinical
associate professor at the Department of Epidemiology, Institute of Public
Health, University of Aarhus, told a news briefing: "Our study shows that
there is an association between drinking a moderate amount of alcohol (about
four to five drinks a week) during pregnancy and lower sperm concentrations
in sons. However, because this is an observational study we cannot say for
certain that the alcohol causes the lower sperm concentrations. It is
possible that drinking alcohol during pregnancy has a harmful effect on the
foetal semen-producing tissue in the testes -- and thereby on semen quality
in later life -- but our study is the first of its kind, and more research
within this area is needed before any causal link can be established or safe
drinking limits proposed."
Dr Ramlau-Hansen and her colleagues studied 347 sons of 11,980 women with
singleton pregnancies who were recruited to the Danish "Healthy habits for
two" study between 1984-1987. Around the 36th week of pregnancy the mothers
answered a questionnaire on lifestyles and health. The sons were followed up
between 2005-2006, when they were aged between 18-21, and semen and blood
samples were collected and analysed.
The researchers divided the sons into four groups, ranging from those who
were least exposed to alcohol (their mothers had drunk less than one drink a
week) -- and this was the reference group against which the other groups
were measured -- to those whose mothers drank 1-1.5 drinks a week, 2-4
drinks a week, or 4.5 or more drinks per week.
They found that sons of mothers drinking 4.5 or more alcoholic drinks a week
had average sperm concentrations of 25 million per millilitre, while the
sons who were least exposed to alcohol had sperm concentrations of 40
million/ml. After adjusting for various confounding factors, they found the
sons in the group most exposed to alcohol had an average sperm concentration
that was approximately 32% lower than that in the least exposed group.
The World Health Organization defines a "normal" level of sperm
concentration as being approximately 20 million/ml or more. Dr Ramlau-Hansen
said: "The reduced sperm concentrations in the most exposed men are rather
close to the lower end of the WHO's normal range for fertility. The
probability of conception increases with increased sperm concentration up to
40 million/ml and so it is possible that the most exposed men could be less
fertile than the least exposed."
She found that semen volume and total sperm count (which also affect a man's
fertility) were associated with prenatal alcohol exposure; these were
highest in sons whose mothers drank 1-1.5 drinks a week. The researchers
could find no association between alcohol exposure and the movement and
shape of the sperm or with any reproductive hormones such as testosterone.
Dr Ramlau-Hansen said: "Our finding that sons prenatally exposed to 1-1.5
drinks per week had higher semen volume and total sperm count compared to
the least exposed group is not surprising and is quite a common finding when
studying alcohol. It could indicate that small amounts of alcohol have a
beneficial effect (for example, on the semen-producing tissue in the foetal
testes), but, in fact, we believe this result may be biased by the
characteristics of the women drinking small amounts of alcohol during
pregnancy or by inaccurate reporting of alcohol consumption. Therefore, it
is not possible to draw a firm conclusion from this result."
The researchers also investigated whether fathers' alcohol consumption had
any effect. "We investigated the association between fathers' total alcohol
intake and semen quality in the sons and found that paternal alcohol was not
associated with semen volume or sperm concentration. This finding suggests
that the observed associations between maternal alcohol consumption and
sons' semen quality are not confounded by lifestyle factors that are shared
by a couple, such as smoking," said Dr Ramlau-Hansen.
She concluded: "If further research shows that maternal alcohol consumption
is a cause of reduced semen concentration in male offspring, then we are a
bit closer to an explanation of why semen quality may have decreased during
the last decades and why it differs between populations. If exposure to
alcohol in foetal life causes poor semen quality in adult life, we would
expect that populations with many pregnant women drinking, possibly heavily,
in pregnancy would have lower fertility in comparison with populations of
where pregnant women do not drink."
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