"Cigarette smoking appears to have an adverse effect on fertility"
1980 United States Surgeon General’s Report
Women who smoke are almost a third less fertile than women who don’t and
are more than three times more likely to take over a year to conceive. It has
been suggested that the reason for this is that the negative effects of
cigarette smoke on hormone levels (see Female
facts) affect crucial processes such as ovulation and also the later
implantation of the zygote (fertilised egg).
It is also thought that the fertilisation process may be affected as the
chemicals in cigarette smoke may cause the cervical fluid to become toxic to
sperm. (see Pregnancy facts)
Some of the toxic constituents of cigarette smoke can cause deformities to
develop in sperm, and damage the sperm’s DNA, causing miscarriage or birth
defects. In fact, men who smoke more than 20 cigarettes a day have an extra 42 %
risk of fathering a child who contracts cancer.
Smoking also diminishes sperm count and reduces the blood flow to the penis,
sometimes causing impotence. Men who smoke are 50% more likely to become
impotent than men who don’t (see Penis facts).