One of the most reliable ways of determining pregnancy is missing a period. You may experience 'implantation bleeding' at the time that your period is due but this is usually lighter and of a shorter duration than your normal period.

It is for this reason that your doctor will ask you when the first day of your last normal period (LMP) was.

Some women continue to have periods throughout their pregnancy but this is very rare.

If you have been planning for pregnancy you have probably made a note of the day you expect to start your next period. Should this not happen, it would be a good time to take a hormone pregnancy test, which you can buy over the counter, or receive from your doctor.

Hormone tests measure the level of hCG (a hormone secreted when you are pregnant) in your urine. Amounts of urine tested can vary, as can levels of hormones produced. The better tests on the market will measure 25-50 mIUs of hCG, which is usually the amount found in urine between the 4th and 5th weeks of gestation.

Bear in mind that the levels of hCG in your urine and blood will be different. First morning urine will always contain the highest concentration of hCG. However, most tests do not require that you use first morning urine. You can increase your chances of having enough hCG in your urine by waiting four hours after your last urination before taking the test, which will allow hCG to build up in your urine.

Hormone tests rarely give false results. A negative result that later turns out to be positive is usually due to the test being performed too early. A positive that later turns out to be a negative may point to a very early miscarriage.

If you have questions about pregnancy test results you can discuss them with your doctor or pharmacist, or refer to the helpline number supplied by the manufacturer of the test.

If you have a positive test result it's a good idea to visit your GP, who will refer you to the pathology department to confirm the result, or you can make an appointment with an obstetrician at your preferred Mediclinic hospital.