How does a pregnancy test work?
Whether taking a urine or blood test, they both measure the levels of human chorionic gonadotropin (hCG)… the pregnancy hormone in the woman testing.
What is ovulation?
Every month (for most women) inside your ovaries, a GROUP of eggs begin to grow within your follicles (follicles are fluid-filled sacs). One will inevitably erupt from the follicle (ovulation)!
Why can’t I test right after ovulation?
The hCG hormone levels rise gradually after egg implantation to the uterine wall. The process is not immediate. After you ovulate, the egg begins it’s journey to a fallopian tube (there are two fallopian tubes present in normal anatomy). It will “patiently” wait there for a mere 24 hours for a sperm cell to fertilize it. Then the fertilized egg must travel to the uterus and implant itself to the uterine wall.
When do you ovulate?
Typically ovulation occurs on day 14 of your cycle. The start of your menstrual cycle begins the first day of your last period. On average, most women have a 28-day cycle (I don’t). A menstrual cycle can vary, if you don’t have a 28-day cycle, there is no need to worry. It’s normal for menstrual cycles to range from 28 to 32 days.
Here’s an overview of a typical 28-day menstrual cycle. (1)
Your cycle begins on the first day of blood flow.
Days 2–14 Follicular Phase
The follicles on your ovary become active, and your cervical mucus starts to thin.
Ovulation occurs mid-cycle, but can vary from between Day 11 and Day 21 of a woman’s cycle. Rising estrogen levels trigger the LH surge, which causes the follicle to ovulate and release an egg. It’s important to chart your basal body temperature and Luteinizing hormone (LH) surge so you know when you ovulate.
Days 15–22 Luteal Phase
After releasing the egg, the follicle produces progesterone, which thickens the lining of the uterus for implantation.
Implantation of a fertilized egg can take place. At this point, hormones produced by pregnancy may be detected by a pregnancy test.
If pregnancy does not occur, your hormone levels begin to fall. The uterine lining sheds, resulting in your period.
Generally, an egg is fertilized in a fallopian tube. Within 9 days, the fertilized egg will travel down a fallopian tube into the uterus and implant to the uterine wall. (2)
Once implantation has occurred, your developing placenta will begin releasing hCG into your blood. (2)
How early can hCG be detected in my urine?
“HCG can be found in the blood before the first missed menstrual period, as early as 6 days after implantation.” (2)
When can I test?
Some women may be able to test earlier for pregnancy than others. We don’t all have the same amount of hCG in our blood in the days after implantation. It may be hard to wait and test, but for most women the best time to take a pregnancy test is in the days after you have already missed your period (when it would normally be due). You may never again feel as anxious as you do in the days leading to your missed period, but if you want to be as sure as you can that you’re accurately testing, you may want to wait. If you don’t mind taking a bunch of pregnancy tests, then by all means take a test, you may be one of the lucky ones. On the other hand, you may want to think twice if you want to avoid the roller coster ride of emotions that are possible if you get a negative pregnancy test. Especially, if you take the test too early, you may actually be pregnant.
For more accurate testing.
“First morning urine should exhibit a higher concentration of the the pregnancy hormone, hCG. This means you can get an accurate result sooner than with other samples collected during the day or evening.” (4)
Read more pregnancy journals by clicking here.
(1) “Ovulation Calculator from WebMD.” WebMD. WebMD, 21 Jan. 2016. Web. 11 Mar. 2016. <http://www.webmd.com/baby/healthtool-ovulation-calculator>.
(2) “Human Chorionic Gonadotropin (HCG).” WebMD. WebMD, n.d. Web. 11 Mar. 2016. <http://www.webmd.com/baby/human-chorionic-gonadotropin-hcg>.
(3) Gnoth, C., and S. Johnson. “Strips of Hope: Accuracy of Home Pregnancy Tests and New Developments.” Geburtshilfe Und Frauenheilkunde. Georg Thieme Verlag KG, n.d. Web. 11 Mar. 2016. <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4119102/#R808-2>.
(4) “First Morning Urine and Pregnancy Test Accuracy.” Early Pregnancy Tests. N.p., n.d. Web. 11 Mar. 2016. <http://www.early-pregnancy-tests.com/firstmorningurine.html>.
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