A sperm test (also known as semenalysis) is to check your partner''s fertility by analysing his sperm. A freshly produced specimen of sperm is examined under the microscope by an expert who will look at the volume of sperm, number of sperm in the sample, how well the sperm move and how many abnormal sperm there are. Normal sperm volume is about 3 millilitres, with 10 milllion sperm per millilitre and at least 40% of these ''normal''. Many things can affect the quality and quantity of sperm, such as smoking, alcohol, certain drugs, infections and stress.
X and Y sperm The diagram shows the penetration of two eggs by sperm containing either an X or a Y chromosome. The egg always has an X chromosome, so an X produces a girl, a Y sperm, a boy.