To understand how a pregnancy test works, it is important to understand how your menstrual cycle works. Do you know how long your normal cycle usually lasts? If you do not, you should start paying attention. Your cycle starts at the beginning of day one of menstruation until the next first day of menstruation. While the average normal cycle lasts approximately 28 days, there are also women who have shorter or longer cycles. It is up to you to determine what is “normal” for you. This is important as it helps you identify the approximate days that you will ovulating. It also helps you detect abnormalities such as missed periods, mid cycle bleeding, including pregnancy! During your menstrual cycle, the body goes through several changes throughout the cycle. One of the most important change is the preparation of the body for possible pregnancy.
Phases of The Menstrual Cycle
The menstrual phase occurs when you are menstruating. It can last from three to seven days or even longer for some women. Remember that “normal” differs from woman to woman. In this phase, the uterus sheds the lining. Some women may experience cramps in the lower abdomen, lower back, or legs. If you have been suffering premenstrual symptoms such as acne, bloating, headaches, etcetera, these symptoms will gradually resolve once the menstrual phase starts. Cramps are the result of the contraction of the uterus that is trying to help expel the tissue. Blood loss can range from 10ml to 80ml.
While this phase also starts on the day one of menstruation, it lasts much longer approximately until day 13 of the cycle. However, the length of this phase is what determines how long your menstrual cycle usually is. It can be shorter or longer depending on your body. In this phase, the pituitary gland in your brain releases a hormone called the follicle stimulating hormone (FSH) that stimulates the growth of follicles in your ovary. Your egg will mature in the follicle. Estrogen is another hormone that helps rebuild the lining of the uterus. Watch this video about follicle development, ovulation, and fertilization!
In the average 28-day cycle, ovulation usually occurs on day 14. However, it can occur from days 11 to day 21 of the cycle depending on the normal length of your cycle. Ovulation occurs when the follicle in your ovary releases a mature egg into the fallopian tube. Before it happens, there is a surge of luteinizing hormone (LH). To understand more about ovulation, click here to watch an animated video of the process.
The luteal phase is also known as the premenstrual phase. In this phase, if the egg is not fertilized, the egg that has been released remains viable for approximately 24 hours before disintegrating and will be shed together with the lining of the uterus during menstruation. If fertilization occurs, the egg will travel through the fallopian tube to be implanted.
How A Pregnancy Test Works
Once conception starts, the body undergoes transformations and changes. One of the first changes that occur is the production of the pregnancy hormone, human Chorionic Gonadotropin (hCG). This hormone can be detected in both your blood and urine. It increases rapidly and doubles approximately every 36 to 48 hours of your pregnancy and peaks at the eight to tenth week of pregnancy. hCG is produced when the embryo implants itself into the uterus. It functions to stimulate the production of the hormone progesterone which helps maintain the lining of the uterus and prevent it from being shed. Some also believe that hCG plays a protective role for the embryo, shielding it from the mother’s immune system as it contains 50% of the father’s DNA which is considered to be “foreign” in the mother’s body.
A pregnancy test works by detecting the level of hCG hormone in your urine. This can be done by urinating on a pregnancy test stick and waiting several minutes as per the directions on the pregnancy test kit. The “stick” has a strip of absorbent fibers. In the strip, there are three zones:
Here, the fibers contain specific molecules (antibody) that attaches itself to hCG.
As the urine moves along the strip, it now carries the antibodies that are attached to hCG. The test zone contains chemicals that will react with the antibodies only if they are attached to hCG. If hCG is present, the colored dye is then released, where you will be able to see a colored line appearing on the test strip. This is known as the test line. If there is no pregnancy, there will be no hCG and no dye will be released. There will be no line appearing on the pregnancy test.
The urine continues moving to the third zone, the control zone where it contains a chemical that will react with the antibodies with or without hCG being attached to them. Again, a colored dye is released, and a line will appear on the pregnancy test. This is the control line to let you know that the test has been completed. When the control line appears without the test line, it is very unlikely that you are pregnant. If both lines appear, chances are you are pregnant!
In other words, if you see one line, you are most probably not pregnant. The keywords to remember is “most probably not pregnant” as a false negative can sometimes occur especially if you try the pregnancy test too early. This means that you are pregnant but the levels of hCG are not enough for detection. If you see two lines, the test is positive, and you should be pregnant. Once you get a positive test result, you should have your pregnancy confirmed by your doctor through a urine test (lab) and possibly an ultrasound. It is recommended that you use the pregnancy test kit at least a day to a week after you missed your period (for accuracy purposes). Here is an image that shows you how to interpret your results!
trong>Are Pregnancy Tests Ever Wrong?
As previously mentioned, there is a possibility that you have a false negative result if you try the pregnancy test too early before there is adequate hCG hormone to be detected. For the most accurate results, it is best to take the test one week after you missed your period. You can also have a false negative if you don’t give the test enough time to work. Try using a timer and wait the recommended time as per the instructions on the package. There can also be a false negative if your urine is too diluted. The best time to take the test is when your urine is most concentrated (in the morning after waking up).
Known as a false positive, this occurs when the pregnancy test indicates that you are pregnant, but you are actually not. It is rare, but it may occur in women who had a recent pregnancy loss where the fertilized egg has implanted but the pregnancy terminated naturally. It can also happen if you are taking fertility drugs that contain hCG. Other causes of a false positive test include ectopic pregnancy, menopause, etcetera.
Alternatives to At Home Pregnancy Tests
While it may sound bizarre, there are many sites that contain information about alternatives of home pregnancy test kits. After conducting some research, I personally think that your best bet is still a home pregnancy test kit as it is much more reliable. However, if you are just curious and want to try some of the following methods out (I do not know nor guarantee if these methods work!), you can try it out at:
- Roundup: 8 super simple homemade pregnancy tests.
- 10 homemade pregnancy test ideas for most accurate results.
- Homemade pregnancy test.
- 8 quick proven homemade pregnancy test for sure results.storknet
These sites uses readily available ingredients such as sugar, bleach, toothpaste (this has recently been debunked), and more. Remember that there is no hard proof that these methods work, so try not to get overly excited or anxious if the homemade tests indicate that you are pregnant. You should confirm it using a home pregnancy test kit that is easily available at any pharmacy or with your doctor.