Smoking Could Harm Sperm, Study Finds09/09/10
THURSDAY, Sept. 9 (HealthDay News) -- Two new studies provide
evidence that smoking can harm sperm - both in smoking men who may
become fathers, and in sons born to women who smoked during
The research also suggests that both men and women who hope to
conceive should kick the habit.
"The results of the present study suggest a negative biological effect of smoking on spermatozoa DNA integrity," said the lead author of one study, Dr. Mohamed E. Hammadeh, head of the assisted reproductive laboratory in the department of obstetrics and gynecology at the University of the Saarland in Saar, Germany.
Research by Hammadeh and his colleagues showed that men who
smoke heavily may experience fertility problems stemming from a
drop in levels of a protein crucial to sperm development, as well
as damage to sperm's DNA.
Another study suggests that women who smoke early in their
pregnancy may ultimately compromise their sons' reproductive
Both studies are published in the Sept. 8 online issue of
In the first study, Hammadeh's team compared sperm from 53 heavy
smokers (more than 20 cigarettes a day) against that of 63
After three to four days of sexual abstinence, a single semen
sample was taken from all study participants, to measure levels of
two forms of a specific type of protein found in sperm, called
protamines. According to the researchers, protamines are key
players in sperm development, helping to spur on the process by
which chromosomes are formed and packaged during cell division.
Hammadeh and colleagues found that in the smoking group, one
form of protamine appeared at levels that were 14 percent below
concentrations observed in the sperm of nonsmoking men. This was
enough to constitute a form of "protamine deficiency" and, in turn,
raise risks for infertility among the smokers.
What's more, smoking-linked "oxidative stress" appeared tied to
an increase in damage to sperm DNA, the team reported.
According to Hammadeh, past attempts to clarify the relationship
between cigarette smoking and male infertility have had trouble
identifying a molecular mechanism underlying any such link. So he
believes the new finding should help convince male smokers
struggling with infertility to kick the habit.
"Because of the fact that cigarette smoke contains mutagens and carcinogens, there have been concerns that smoking may have adverse effects on male reproduction," Hammadeh noted. The new findings help bear that out, he said.
The second study was led by Dr. Claus Yding Andersen, a
professor of human reproductive physiology at the University
Hospital of Copenhagen in Denmark. It focused on the impact of
maternal smoking during the first trimester of pregnancy upon the
development of the male fetus.
In this case, the authors analyzed tissue from the testes of 24
embryos that had been aborted between 37 and 68 days following
After classifying the prospective mothers according to smoking
habits, the research team found that the number of so-called "germ
cells" -- cells that develop into sperm in males and eggs in
females -- were 55 percent lower in the testes of embryos obtained
from women who smoked. This observation held regardless of the
mother's alcohol and coffee consumption habits.
As well, embryonic levels of so-called "somatic cells" (those
that go on to form other types of tissue) were 37 percent lower
among those women who smoked.
In both the case of germ and somatic cells, drop-offs in levels
appeared to be "dose-dependent," meaning that the more the
prospective mother smoked, the lower the number of cells grown by
Based on these findings early in fetal growth, Anderson and his
colleagues conclude that the apparent impact of smoking on cellular
production might continue in male offspring carried to term. And
that could mean a higher risk of impaired fertility in sons.
According to the Danish team, their earlier research involving
female embryos also revealed "germ cell" reductions of about 40
percent for embryos taken from women who smoked during pregnancy.
This suggests that maternal smoking in pregnancy may harm the
reproductive health of both male and female offspring.
"Our results provide health care professionals who talk to women who are considering conceiving, or have conceived just recently, with a 'here and now' argument to convince them to stop smoking," Anderson said. "Because the negative effect of smoking appears to take place right from conception and during the early days [of gestation], when the human embryo becomes differentiated into either a girl or a boy."
There's more on the dangers of smoking during pregnancy at the
March of Dimes.
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