Since the earliest recorded history, women have had a strong desire to know whether they are pregnant as early as possible. The body goes through countless changes in the first trimester, and one of the first indicators is a change in the hormones that leave the body through urine.
Ancient Egyptians relied on a form of urine testing to determine pregnancy status way back in 1350 BCE. A woman urinated daily on wheat or barley seeds and if the plants grew, it meant she was pregnant. Modern-day validation suggests that test was about 70% accurate in detecting human chorionic gonadotropin (hCG), a hormone produced by a woman’s body soon after implantation of a fertilized egg inside the uterus.
Thankfully, urine-based pregnancy tests have evolved substantially. Women now have access to advanced tests that can detect a pregnancy as early as eight days after ovulation. But while many home pregnancy tests are marketed as simple and effective, getting accurate results comes down to how early in your ovulation cycle you take the test.
Ovulation generally occurs around day 15 of a 28-day cycle. In a normal pregnancy, an egg is fertilized in the fallopian tube and then travels into the uterus, where it implants in the uterine wall. After implantation, production of hCG starts from cells in the developing placenta (tissue that will feed the fetus). Trace levels of hCG can be detected as early as eight days after ovulation.
That means you could get positive results several days before you expect your period to start. However, the first part of your cycle is more variable than the second, making it tricky to determine the best time for an early test.
Pregnancy test accuracy
Each type of pregnancy test is designed to detect a set minimum level of hCG. This is why pregnancy test manufacturers advertise the way they do: “Know four days sooner,” or “Accurate up to six days before a missed period.” However, while home pregnancy tests are quite accurate – many boast a 99% detection rate based on laboratory testing results – marketing claims can be misleading.
For example, a 99% detection rate means a test can detect hCG 99% of the time on the day you miss your period. These statistics also assume that women are testing at the optimal time and following all instructions correctly.
Many home pregnancy tests available today are midstream urine dip tests, which are the traditional “pee-on-a-stick” tests and are fairly easy to use. There also are tests in which you pee into a cup and dip a test strip into the urine. The New York Times published a story ranking the best home pregnancy tests, citing a midstream test with an ergonomic grip as the easiest to use and most accurate.
Research has shown that average test results when women used the dip tests matched lab test results just 70% of the time, whereas 99% of women typically can get an accurate reading from a midstream test.
You should wait to take a pregnancy test until the first day of your missed period. Since HCG is only present once implantation of the egg occurs, there often isn’t enough of the hormone to be detected until you miss your menstrual cycle.
“Pregnancy tests pick up the hormone secreted after implantation, which usually occurs about two weeks after the sperm meets the egg,” says Dr. Culwell. “For women who have regular periods, this usually means that HCG can be detected as soon as you miss a period.”
This, of course, assumes you have a regular menstrual cycle that can be easily tracked and predicted. If this isn’t the case, you may choose to instead track ovulation, or when an egg is released and makes its way to the uterus where it can potentially be fertilized. An at-home ovulation predictor kit can help you track fertilization.
If this method is used, it’s best to take a pregnancy test “approximately 14 days after a documented ovulation,” says Zaher Merhi, M.D., an OB-GYN, reproductive endocrinologist and founder of Rejuvenating Fertility Center with locations in New York and Connecticut.
Signs You Should Take A Pregnancy Test
The biggest indicator it’s time to take a pregnancy test is a missed period. It isn’t the only sign, however. Symptoms that signal it may be time to take a pregnancy test, according to Dr. Merhi, include:
- Missing a period
- Breast fullness/soreness
- Frequent urination
- Nausea
- Vomiting
- Fatigue
- Abdominal bloating
When Is the Best Time to Take a Pregnancy Test?
You can take a pregnancy test any time of the day. But if there’s a chance you’re early in pregnancy, take it in the morning when your urine is most concentrated so the test can more easily detect the HCG hormone, says Dr. Culwell.
“The best time in the cycle to take a test would be after you have missed a period,” says Dr. Culwell. “This will make it less likely that you might miss an early pregnancy if the HCG levels are too low to be picked up by the test.”
Where To Buy A Pregnancy Test
You can buy a pregnancy test at most drug stores and grocery stores, or even online.
How Soon Can You Take a Pregnancy Test?
At-home pregnancy tests are regulated by the Food and Drug Administration (FDA), meaning their accuracy and labeling is evaluated before they reach store shelves. When it comes to the accuracy of at-home pregnancy tests, research shows if the test is used as directed, an inaccurate result is rare. While false-positive pregnancy test results are uncommon, if you do receive an inaccurate result, it’s more likely to be a false-negative. In this case, it’s likely you’re testing too early, before HCG can be detected.
“For most women who have a regular menstrual cycle, a pregnancy test could be taken on the expected day of the period,” says Dr. Merhi. “The earliest [time to test] would be the expected day of the period; however, I usually tell patients to wait at least a few days (or one week) after the expected day of the period in order to lower the chances of having a false result.”
It’s worth noting that at-home pregnancy tests accuracy claims—many of which advertise an accuracy rate of 99% from the day of the expected period—are based on data used in a sterile laboratory testing environment. If you think you received an inaccurate result, you can either wait and test again a few days later or see your doctor for a blood test, which can detect HCG earlier than at-home tests and has an accuracy rate of 99%.