Home Pregnancy Test Guide: When and How to Take a Pregnancy Test

Originally published 12/18/2019. Updated for accuracy and relevancy on 11/13/2023.

Have questions about using an at-home pregnancy test? We’ve got all your answers.

By Halle Tecco, MBA, MPH

How Does a Pregnancy Test Work? 

Pregnancy tests detect a hormone called human Chorionic Gonadotropin (hCG), which can be detected in urine or blood after an embryo implants itself into your uterine wall. hCG is the first detectable sign of pregnancy, and home tests (like the Natalist Pregnancy Test) are an easy and reliable way to determine if you’re pregnant.

How Early Can I Take a Pregnancy Test?

You can use either a midstream test or pregnancy test strips starting five days before you expect your period to start. For the most accurate results (over 99%), test three days before your expected period. 

If you get a negative result and tested more than three days before your expected period, you could still be pregnant (see chart). We recommend taking another test in a few days. Since it would be really early in your pregnancy, you may not have enough hCG for the test to detect yet. In just two days, your hCG levels will usually double. The more hCG your body makes, the more likely you are to get a positive result.

What Time of Day Should I Take a Pregnancy Test?

If you’re testing before your expected period, it’s best to test first thing in the morning (when your urine has a higher concentration of hCG), but you can still test at any time of the day. Keep in mind that drinking a bunch of liquid in the few hours before testing can dilute your urine and cause a false negative result (meaning you could be pregnant, but the test will show you’re not).

When to Test for Pregnancy With an Irregular Period

15% of women have irregular periods, which can make it harder to predict when to test. If this is you, try counting at least 14 days from when you had sex. If your test says you’re not pregnant and you think you might be, test again tomorrow or in a few days. 

How to Read Pregnancy Test Results

After following the instructions to take the test, you can view your results in the test window. The test window shows two lines—one for the control line (C) to make sure the test worked and another, the test line (T), that shows a positive result.

Positive Pregnancy Test Result

If two lines show up, even if the test line (T) is very faint, that’s a positive—or pregnant result.

Negative Pregnancy Test Result

If only the control line (C) shows up, the test didn’t detect hCG. Either you’re not pregnant or it’s too early to test.

Invalid Pregnancy Test Result

If only the test line (T) shows up, or no lines develop, the test result is invalid, which usually means the test is faulty and did not detect the hormone. This could mean the absorbent tip wasn’t saturated with enough urine, or the test is expired or damaged. Grab another test and try again. If you still get an invalid result, contact us.

Can You Get a False Negative Pregnancy Test?

A negative result means the test did not detect hCG in your urine. A false-negative result (when the pregnancy test is negative, but you’re actually pregnant) can happen for two reasons:

1. Either your urine was too diluted (don’t drink a lot of liquid for a few hours before testing) or 
2. It’s too early to detect a pregnancy. If you tested before your expected period, this could be the case. If you feel you’re pregnant, test again in a day or two. hCG levels soar in early pregnancy—doubling every 48 hours. If you miss your period and still get a negative result, see your doctor.

It’s really rare, but if after five minutes you see no lines or only a test line (T), the test either wasn’t saturated with enough urine—or it’s defective or expired (check the wrapper). Throw it out and try again with a new one. 

What Can Affect Pregnancy Test Results?

• Fertility drugs containing hCG (such as Pregnyl and Profasi). Drugs containing hCG usually clear your body two weeks post-injection.
• A recent miscarriage or pregnancy, including a chemical pregnancy (a pregnancy loss very soon after implantation). This may give you a false-positive result when you’re no longer pregnant.
• Rare medical conditions that result in the production of hCG unrelated to pregnancy. These include gestational trophoblastic disease, ovarian tumors, and hCG secreted by the pituitary gland during menopause. If you think this could be you, talk to your doctor.
• Following instructions incorrectly. 
• Waiting too long to read your results. Results read after 15 minutes aren’t accurate.

Bleeding After a Positive Test Result

Bleeding after a positive pregnancy test result can point to many different things, including a chemical pregnancy, implantation bleeding (check out this article on spotting by Dr. Mare), and other factors. You should speak to a healthcare provider to confirm your pregnancy test results and to discuss any potential complications. 

Prepare for Pregnancy With Natalist

Pregnancy tests are an extremely useful tool for getting clear answers about your reproductive health in the comfort of your own home. There is a long list of options when searching for pregnancy tests, from digital tests to analog test strips. Just make sure that you are following the instructions exactly to get an accurate result. Natalist is proud to offer sensitive, early-result pregnancy tests. You can even bundle and save when you get a hormone fertility test or ovulation tests as well. Learn more about testing for pregnancy on the Natalist blog.