Becoming pregnant requires several steps. These includes fertilization by a sperm and traveling to the uterus to implant into the uterine wall. This causes the placenta that will ultimately nourish the baby throughout the pregnancy to grow. The cells in the placenta make and secrete human chorionic gonadotropin (hCG). This is known as the “pregnancy hormone.” According to the American Pregnancy Association, the increasing hormone levels of hCG can be detected via a urine test as early as 12 to 14 days after conception.
When you purchase an at-home pregnancy test, you are given a small, plastic applicator that you urinate on. The urine then reacts with chemicals designed to detect hCG. If hCG levels are above a certain amount of the hormone, the pregnancy test will read “positive.”
Advancements in chemical testing materials have meant that pregnancy tests have become more “sensitive” to the hCG hormones that can indicate you’re pregnant. Note the most sensitive early pregnancy test isn’t one you can necessarily do at home. It’s a blood test, which can detect increases in hCG levels as early as 11 days after conception, according to the APA.
How Is Sensitivity Determined?
A “sensitive” pregnancy test measures the amount of hCG hormone in your urine at the lowest possible levels. Some pregnancy tests on today’s market can measure hCG levels at low levels of 5 miU/ml. Others measure hCG levels at 25 miU/ml. A woman’s hCG levels will double every two to three days when she becomes pregnant. This means that even if a sensitive pregnancy test shows a negative, taking the test two to three days later may reveal positive results as your hormones increase.
If you are wondering just how sensitive a pregnancy test may be, the package will usually state its level. For example, the First Response Early Result pregnancy test has a sensitivity of 6.3 miU/ml. This is a very sensitive at-home pregnancy test that claims it can detect pregnancy six days faster than most competitor’s tests. Many at-home pregnancy tests, such as the ClinicalGuard Pregnancy Test, New Choice Pregnancy Test, and the ClearbluePlus Pregnancy Test have a sensitivity of 25 miU/ml.
How Do I Choose A Pregnancy Test?
The availability of affordable and sensitive pregnancy tests means expectant moms can find out they may be pregnant earlier than ever. However, it’s important to remember a few caveats when it comes to pregnancy testing. First, many women will use a pregnancy test several days after a missed period. According to CBS News, an estimated 10 percent of pregnancy women’s embryo doesn’t implant into the uterus until 10 days after fertilization. This means the embryo isn’t yet releasing hCG because it hasn’t implanted. A woman is therefore pregnant, but a traditional urine test won’t detect it. Conversely, some women may have a pregnancy that will result in early miscarriage that will cause a short-term rise in hCG, but the woman won’t have a pregnancy that carries to full term.
Keeping these things in mind, remember that when you choose a “sensitive” pregnancy test, it’s always possible the results may change. If you have a specific question, contact your obstetrician for more information.