ABSTRACT
It is estimated that there are some 1.2 billion women of
reproductive age in the world today. If on average each
woman has two acts of intercourse per week this will amount
to some 114 million acts of sexual intercourse taking place
each day, resulting in 910 000 conceptions and 356 000 sex-
ually transmitted bacterial and viral infections. There are
more than 250 million new cases each year, at least one
million of which will be HIV infection. Some developing-
country family planning, antenatal, and maternal and child
health clinics find that as many as one or two women in every
10 are infected with an STD. 1
Reproduction in animals is characterized by a vast over-
production of sperm and eggs and a high degree of wastage
of early pregnancy. A single human ejaculate represents
more potential human beings than are found in the whole
of the southern USA and Central America (Figure 2.1).
