Am I pregnant? How early can I test?
If you and your partner are trying to conceive, one of the hardest parts is the waiting. The infamous two week wait is enough to frustrate even the most patient woman. The question thus arises, do you need to wait two weeks? With advances in technology it is now possible to detect pregnancy from the convenience of your own home before you have even missed your period. How early you can test depends on the type of test you are using.
How pregnancy tests work
Whether you are having a blood test done in a lab or using a urine test as home, the both work by detecting the hormone hCG. There are several types of tests done in the lab that can detect hCG. Many doctors use the same type of test as the kits used in home pregnancy tests. These tests work by using a substance that changes color once it is bound to hCG. Blood tests can be used to determine the exact amount of hCG being produced by the woman whereas urine tests are limited to determining whether or not hCG is present at a high enough level to confirm pregnancy. A pregnancy test is considered positive if the hCG level is 5 mIU/L or above.
What is hCG and when will I begin producing it?
To understand how pregnancy tests work it is helpful to know what hCG is and the basics of early fetal development. HCG, or human chorionic gonadotropin, is produced very early in pregnancy and serves several functions to support the developing baby including stimulating progesterone and estrogen production.
As pregnancy begins, your baby goes through many phases of development. A woman's egg and man's sperm unite on fertilization to form what is technically now called a zygote. The zygote goes through rapid division eventually forming an outer layer called a trophoblast. The trophoblast will begin secreting hCG during early pregnancy. This does not occur until your baby implants into the uterus. Ovulation and fertilization typically occur midway through a woman's menstrual cycle, usually around 14 days after the start of menses. If fertilization occurs, the zygote will travel down the fallopian tube towards the uterine cavity. Around seven to nine days after fertilization, your baby will implant deep into the uterine wall. Your body will not begin producing hCG until then. Once your body has begun producing hCG you should be able to determine pregnancy through a home pregnancy test.
When is the earliest you can take a pregnancy test?
Newer home pregnancy tests detect very small amounts of hCG, some as low as 5 mIU/L. With these very sensitive tests, it is possible to test positive as early as seven days past ovulation. It is important to remember that implantation occurs anywhere from seven to ten days past ovulation and women produce varying amounts of hCG, eventually forming a pattern of doubling hCG amounts every two to three days. While it is possible to test positive as early as seven days past ovulation, there is also a good chance that implantation has not occurred yet or that you are not producing hCG at a high enough level to be detected by a home pregnancy test. For best results, it is still recommended to wait until a woman has missed her period or 14 days past ovulation. For those that just can't wait, the very earliest you should test is seven days past ovulation.
You might also be interested in JM's Pregnancy Test Accuracy Chart.
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