When you’re trying to get pregnant, the two-week wait to take a pregnancy test can seem endless. It’s natural to feel tempted to scan the drugstore shelves for a pregnancy test promising accurate results before your period is set to arrive. But you may wonder: can I trust the results that early?
Here we answer your most pressing questions about how soon to take a pregnancy test. You’ll also learn to avoid getting an unreliable positive result due to a chemical pregnancy.
How soon can I take a pregnancy test?
Ideally, wait until the first day of your missed period. That’s when pregnancy tests are most reliable, although some tests may be used as early as 4 to 5 days before your menstrual cycle begins(1). However, the timing of your cycle and implantation both influence the accuracy of your test, as we explain later in this post.
How accurate is a home pregnancy test?
Most home pregnancy tests claim to be accurate 99% of the time, as long as you carefully follow the instructions and take the test inside a certain window of time. However, a medical manual widely used by doctors maintains the accuracy rate is closer to 97%(2). How you use the test may affect its accuracy.
How may I improve the accuracy of a home pregnancy test?
The accuracy of a home pregnancy test may vary, based on how you use it and your menstrual cycle. It may be possible to improve test accuracy by:
Are home pregnancy tests more accurate for some women than others?
Your menstrual cycle and the time of implantation affect test results. Nearly one-third of women have cycles that vary by more than 13 days(5). In addition, a fertilized egg may implant in your uterus at different times. In as many as one in 10 women, implantation occurs after the first day of a missed period(3). Taken together, these factors suggest home pregnancy tests may be accurate for some women, but not for others, as soon as 1 day after a missed period.
What do pregnancy tests measure?
Pregnancy tests measure a hormone called human chorionic gonadotropin (hCG), a pregnancy hormone. HCG is produced by the trophoblast, a layer of tissue that nourishes the embryo and later forms part of your placenta(6). HCG appears shortly after the embryo attaches to the wall of your uterus.
When does hCG appear in my urine?
If you have a 28-day menstrual cycle, you can detect hCG in your urine 12 to 15 days after ovulation. If you take a test too early, the test may not detect enough hCG to yield a positive result.
It’s not uncommon to inaccurately estimate when your period is set to arrive. Because of this, and because many women have irregular periods, 10 to 20 pregnant women out of every 100 will not detect their pregnancy on the first day of their missed period(4).
Why does a chemical pregnancy cause a positive test result?
A positive pregnancy result may cause unnecessary heartache when the positive result is from a chemical pregnancy. A chemical pregnancy is one that ends naturally before 5 weeks, before your doctor sees the gestational sac on an ultrasound(7). Most of these pregnancies end because of chromosomal issues(8). Chemical pregnancies are common, happening in 50-60% of first pregnancies(9). Typically, you see a positive test result, followed by a negative one. You may avoid a positive test result from a chemical pregnancy by waiting until well after your period is due to take a pregnancy test.