Blood or urine?
Waiting for two little pink lines to appear on a urine stick can be quite stressful. But home pregnancy tests are accurate – when done correctly and at the right time. It is best to wait until after you have missed a period before you do a home pregnancy test.
Blood pregnancy tests can, however, show accurate results before a woman misses her period. While most women can safely do their own pregnancy test, couples using in-vitro-fertilisation programmes are carefully monitored for the first signs of pregnancy and blood tests will be done when needed.
Women who have had repeated miscarriages may need progesterone injections to prevent another miscarriage, and should have a blood pregnancy test as early as possible.
Read: Understanding ovulation
How does it work?
About eight days after conception the fertilised egg produces a hormone called hCG (human chorionic gonadotropin). This keeps the egg alive until it reaches the safety of the womb.
A blood test measures the amount of hCG in the blood, while a home pregnancy test measures the amount in the urine. If hCG is present, then this confirms that you are pregnant. Most home tests show results after 40 seconds. If there is no change after five minutes, the test is considered negative. After 10 minutes the test is no longer valid.
When should I do the test?
Testing too early can result in a false negative test as there is not enough hCG in the system. This is because, although the baby’s due date is calculated from the first day of your last period, conception only actually happens two weeks later, after you’ve ovulated.
While most women conceive about two weeks after their period, women who ovulate later will also conceive later. Remember, conception doesn’t always happen immediately after sex.
Read: Best positions for conception
If the egg takes its time getting to the fallopian tube, the vagina and cervix (mouth of the womb) take care of the sperm by creating a sperm-friendly zone that preserves them for up to five days or until the egg makes her appearance. This means that conception can happen as late as five days after having sex.
If you do a pregnancy test before ovulation, your test will be negative. It’s safest to wait until you have missed a period to do a home pregnancy test because by then the hCG will be in abundance.
If a woman is sure about her dates and monitors the signs of fertility, she can safely test her urine earlier and get accurate results