Home pregnancy tests are one of the easiest and most effective ways to determine if you are going to have a baby or not.

But while they’ve been around for 40 years now, there are lots of myths out there surrounding their accuracy and the things they can tell you.

Pregnancy tests are designed to tell if your urine contains the hormone human chlorionic gonadotropin (hCG) that is produced when a fertilised egg attaches to the wall of a woman’s uterus. This can also be determined via a blood test.

Many of the home pregnancy tests you purchase at the supermarket or chemist claim that they are more than 99% accurate if you use them on the first day of a missed period or earlier.

Here are some of the things you might have heard about home pregnancy tests and aren’t sure whether they’re true or not:

1. Pregnancy tests can reveal the sex of your unborn baby

Unfortunately, no matter how keen you are to find out if you are having a boy or a girl, you can’t do it by peeing on a stick. There are no sex hormones contained in urine, and the amount of hCG you produce increases at the same rate regardless of whether you are having a girl or a boy. So a urine test just can’t tell you what the gender of the baby is. The only reliable way to confirm your baby’s sex is to have an ultrasound between 16 to 20 weeks.

2. You can get a positive test on an at-home test straight away

While pregnancy tests are generally pretty accurate, the results are going to vary depending on the brand. And quite often, you won’t get an answer immediately. It can take around five days for a fertilised egg to implant itself in the uterus and stimulate the production of hCG. At this stage, the results can be barely detectable and it can take another week before there’s enough hCG in your system to trigger a result on a pregnancy test. Some brands of pregnancy tests promise results early due to their sensitivity, while others require you to have missed your period in order to gain an accurate result. In a nutshell, just because the pregnancy test is negative doesn’t mean you’re not pregnant. You might have just done it too early for the hCG to be detected.

3. You can’t get a false positive

There are a lot of things that won’t affect the way your body produces hCG no matter what you might have heard – this includes things like exercising, stress, drinking, smoking and the food you eat.

However, some fertility treatments contain hCG which can lead to a false positive. This can be a real disappointment for someone who has been trying really hard to get pregnant to find that the test was wrong.

If your pregnancy is healthy, the hCG levels will double every two to three days. At home tests only measure if you have hCG present, and don’t let you know the exact amount you have. So they can also show you are pregnant even after you have had a miscarriage.

4. There are cheap, natural alternatives to tell if you are pregnant

There’s all sorts of information floating on the Internet that claims you can make DIY tests to save money. This can include everything from using bleach and peeing on dandelion leaves, to shoving an onion up your hoo haa and leaving it there overnight. This is all quackery and not even remotely scientific. You might save some money by not purchasing a legitimate pregnancy test, sure, but any results you get aren’t going to be reliable.

5. If the result is faint or hard to read, you’re not pregnant

Sometimes, the result on a positive pregnancy test will be fainter or darker than the control line. This could be because there is less hCG in your urine when you’re early on in pregnancy. A positive is a positive. However, if there is a shadow line where the positive test should be, you should disregard it if you can’t see it when holding it at arms length away from you and you should test again the next morning.