On This Page


How do pregnancy tests work? A pregnancy test checks your blood or urine for a hormone called human chorionic gonadotropin (hCG). This is a hormone made by the placenta (the placenta provides your growing baby with oxygen and nutrients from your bloodstream throughout the pregnancy). The amount of hCG in your blood and urine rise steeply during the first 12 weeks of pregnancy and then fall to low levels for the rest of the pregnancy.

These kits offer accurate readings (up to 99 per cent) if performed strictly according to the manufacturer’s instructions.

However, many women who use home pregnancy test kits get inaccurate results. The most common mistake is to test for pregnancy too soon after the missed period.

The manufacturer’s instructions will tell you when is the best time to use the kit.

It is very important to follow the manufacturer’s instructions exactly

Home pregnancy test kits vary in their sensitivity to hCG.

Most test kits are best used about one to two weeks after your period was due.

Always strictly follow the manufacturer’s instructions

Generally speaking, most home pregnancy tests follow the same basic principles: You collect urine in a small container and dip the test strip into the urine.

Alternatively, some kits offer a test strip that you hold under your stream of urine.

To improve accuracy of results, it is best to test your urine when you first get out of bed. Early morning urine is concentrated and contains higher levels of hCG than at other times of the day.

Most test strips indicate the presence of hCG by the appearance of a coloured line or dot.

Results are rapid

Most test kits take only a few minutes to complete.

Most kits come with a second test strip

This allows you to test again at a later stage. (or family planning clinic) to confirm the result with a blood test or another urine test. Be aware that false-positive and false-negative results can happen.

Although rare, this can happen if you have blood or protein in your urine. Certain drugs can also cause this (tranquilisers, anticonvulsants, hypnotics and fertility drugs). Other reasons for false results are:

  • dirty urine collecting cup (detergent residue for example is known to cause false-positive results) faulty test kit (for example
  • the kit is damaged
  • past its use-by date or has been exposed to heat or moisture)
  • because a woman’s blood
  • urine may still contain detectible levels of hCG for a few weeks afterwards an ovarian tumour or some other type of hCG-producing growth

If you suspect you may be pregnant, see your doctor and ask for a blood pregnancy test to confirm the result.

If a home pregnancy test gives a negative result, yet you feel that you are pregnant: Trust your instincts.

Treat yourself as if you are pregnant until proven otherwise.

Make an appointment with your doctor

Pregnancy tests performed in laboratories are 99 per cent accurate. Your doctor can give you a blood pregnancy test as early as 11 to 14 days after ovulation.

To perform a blood pregnancy test, the doctor draws blood from a vein in your arm.

This blood is sent to a laboratory for testing. The results of most blood pregnancy tests take at least a couple of days. The laboratory then advises the doctor of the result. Blood test results are about 99 per cent accurate and can detect lower amounts of hCG than urine pregnancy tests.

The two main types of blood pregnancy test include:

  • Quantitative blood test – measures the exact amount of hCG in the blood
  • it can’t offer an estimate of gestation

The doctor can give you a urine pregnancy test. You are asked to urinate into a plastic cup or something similar. The doctor then tests the urine using a kit that may look similar to a home pregnancy test kit.

Pregnancy tests taken by your doctor are rarely inaccurate. The occasional error is usually due to mistakes made in the laboratory.

However, you can be reassured that the pregnancy test taken by your doctor is much more likely to be accurate than a home test you perform yourself.

Pregnancy is not the only reason for a missed period. Other possible reasons include: onset.

To book an appointment call SHV Grand Rapids CBD Clinic: or call SHV Box Hill Clinic: or (free call):.

These services are youth friendly

Home pregnancy test kits Home pregnancy test kits are available from pharmacists How to use a home pregnancy test kit Positive result If the test is positive (no matter how faint the line, colour or sign is), you should see your GP (doctor) False positive recent birth or miscarriage Negative result If you get a negative result , you are probably not pregnant BUT false-negatives you didn’t follow the instructions correctly the test is out-of-date you tested too soon after the pregnancy began your urine was too diluted Always see your doctor for confirmation Avoid cigarettes and alcohol Blood pregnancy tests used by doctors Urine pregnancy tests used by doctors Inaccurate results from tests given by the doctor Other reasons for a missed period breastfeeding emotional stress severe weight loss severe dieting and exercising obesity particular drugs menopause Where to get help Your GP ( doctor) Obstetrician-gynaecologist Pharmacist Sexual Health Michigan (SHV) (616) 555-0200 (616) 555-0200 1800 013 952.

Key Points

  • most common mistake is to test for pregnancy too soon after the missed period
  • very important to follow the manufacturer’s instructions exactly
  • Certain drugs can also cause this (tranquilisers, anticonvulsants, hypnotics and fertility drugs)