How Does a Pregnancy Test Work?

Even when using a condom and birth control, it’s still possible for women of all ages to unintentionally become pregnant. Modern over-the-counter pregnancy tests have enabled women to determine whether or not they are pregnant without professional assistance. So, pregnancy tests help women decide if they’re going to receive an abortion. Read on to learn more about pregnancy tests, how they work, and when women should take them.


Why do Women Receive Pregnancy Tests?

Generally, women take pregnancy tests when they are experiencing pregnancy symptoms. Some, however, may also take a pregnancy test if they have doubts about the effectiveness of the birth control. These are some of the most common reasons that women take pregnancy tests:

  1. Missed period: When you’re having sex on a regular or semi-regular basis, you should always track your periods. This is true whether you’re using contraceptives or not. While it’s possible to miss a period because of other factors (like stress and diet), it can often indicate pregnancy. Even while pregnant, women may experience spotting, without full-blown menstrual bleeding.
  2. Cramping: Menstrual cramps may also stem from pregnancy, especially when the period does not follow. If you are experiencing menstrual cramps that do not lead to a period, then consider taking a pregnancy test.
  3. Painful feeling in breasts: Pregnancy causes the body to produce more hormones (estrogen and progesterone), thus causing heightened blood flow as well. Because of this, the breasts may feel especially tender, with some level of discomfort.
  4. General Discomfort: While this may seem general, it’s true. Especially if you have another reason to believe you are pregnant, pay attention to how you feel on a day-to-day basis. Pregnancy can cause random feelings of nausea, fatigue, and reactions to certain food, among other things.
  5. Failed contraception: Both birth control and condoms are excellent pregnancy prevention tactics. Unfortunately, though, they occasionally do not work. If you have any reason to believe that your contraception failed, then consider taking a pregnancy test.


How Does a Pregnancy Test Work

Pregnancy tests help determine whether or not a woman is pregnant based on the presence of a hormone. This hormone, called human chorionic gonadotropin (hCG), generally indicates pregnancy.

The Primary Factor: hCG Production

After being fertilized in the Fallopian tubes, the egg moves into and embeds itself within the uterus. It then begins to produce hCG. This subsequently causes the mother to release progesterone, keeping the uterine lining in place. These chemicals are then released in the mother’s urine.

Zone 1: The Reaction Zone

Shaped in the form of a stick, pregnancy tests are designed to detect certain chemicals in the urine. They do so by gradually absorbing the urine as it travels up the stick. There are three distinct zones in which the stick tests for this hormone. The reaction zone contains absorbent fibers, which have an antibody that attaches itself only to hCG.

Zone 2: The Test Zone

As the urine continues to travel up the stick, it carries these antibodies over to the second area, the test zone. The test zone contains a unique chemical that reacts with these antibodies, but only when hCG is present. If this is the case, it subsequently releases a colored dye, creating a colored line on the test strip. If the woman is not pregnant, then no line will form.

Zone 3: The Control Zone

After this critical step, the urine progresses to the control zone, or the third area of the pregnancy test. In this area, there are chemicals that react with the antibodies, whether or not there is hCG present. This area then releases a dye, which causes a line to appear on the test strip.

If the control line and the test line appear, then the test worked and the woman is pregnant. If the control line appears and the test line does not appear, then the test worked but the woman is not pregnant. If the “control” line does not appear, then the pregnancy test was ineffective. When this occurs, we recommend that patients visit a gynecologist for a blood, pelvic or sonogram test.


Free Pregnancy Testing on Long Island

At Stony Brook Women’s Health, we are committed to helping all of our patients make the right choice for them. We supply urine pregnancy tests to all of our patients free of cost. Our experienced and caring staff will educate all patients about the potential options, and enable them to take the appropriate step.