hCG (Human Chorionic Gonadatropin) is the hormones most commonly associated with pregnancy. It’s the hormone that pregnancy tests test for. Some tests are more sensitive than others, although not all tests show the minimum hCG level measured on the box when you buy it. The lowest level of hCG that a pregnancy test will measure is 25 mIU/mL. Some pregnancy hCG strips can measure as low as 10 mIU/mL. As a pregnancy goes on, the hCG levels increase and double every 48-72 hours. So, the farther along a woman’s pregnancy is, the more likely her hCG levels will register on a pregnancy test.
There is an old question about whether a person can get a “false negative” or a “false positive” on a pregnancy test. A false negative certainly is possible if the hCG levels are too low to register on the pregnancy test. If a woman has not gotten her regular period and the pregnancy test registers as negative, the woman is encouraged to re-test in a few days or get a beta blood test done. Since hCG levels are usually only associated with pregnancy (and to a lesser extent, a woman’s menstrual cycle), common sense is that a false positive on a pregnancy test is nearly impossible.
Yet, here is where common sense fails… hCG is sometimes administered as an injection to help women with fertility challenges. This is what I did during my Cycle #2 for my IUI. I took 10,000 mIU of Pregnyl. hCG is said to trigger ovulation and to lengthen the luteal phase of her cycle so that she will have a higher chance of conceiving. Lack of ovulation is a common reason why a couple has problems conceiving. So, getting an hCG injection is seen as something that can be quite helpful in a couple’s fertility quest.
My Pregnyl Trigger Shot
Unfortunately, if a woman has gotten an hCG shot, her blood and urine hCG levels will likely reflect the hCG that she’s had injected, rather than the hCG from her potential new pregnancy. So, it’s often possible for a woman who is not pregnant to get a positive result on a pregnancy test if she’s recently had an hCG shot.
The Agonizing TWW (Two-Week Wait)
Home pregnancy tests (HPT’s) for the presence of hCG in the urine. Once you receive the hCG trigger shot, you will test positive for hCG and will get a positive result on a pregnancy test. All these are false positives, and doesn’t mean you are pregnant.
This is exactly what happened to me a full 10 days after I took my trigger shots. On all my hCG strips, I saw some sort of 2nd line, even though the last 3 were super faint.
You might hear your doctor talk about hCG’s “half-life” and why you can’t test right away. So, what is your doctor talking about? The half-life is the amount of time it takes for the medication to lose half of its activity. hCG has a half-life of about 28 hours, meaning that approximately every day, your hCG levels from the shot will drop in half.
How long you have to wait before it’s “out of your system” depends on the dosage of your trigger shot, the sensitivity of the pregnancy tests you use, and individual variations in how different women metabolize and excrete the drug. hCG could stay in one woman’s body for more than 14 days but be gone after 7 days in another woman.
If you need to find out sooner, you can do some math and figure it out. Again, hCG has a half-life of 28 hours in your body, which means that your hCG levels should decrease by half every 28 hours. Everyone’s body is different, but the general rule of thumb is 1000 units per day, so your 10,000 unit shot, you’ll need to wait at least 10 days after the shot to take the pregnancy test. The 5,000 unit shot, will have you waiting at least 5 days.
If you’ve had the trigger shot, how will you know if you are pregnant or not?
The first method is the really old fashioned method, which is to wait to see if your period comes when it is supposed to. This is not satisfying at all, and will likely take all the patience you have, especially knowing that pregnancy tests are available, but won’t work for you.
Your last option would be two beta blood tests at your doctor’s office, taken a few days apart in order to see if your hCG levels are increasing or decreasing.
Each person’s journey to conception is different. For some women that journey involves an hCG shot. It may be the therapy that works, but you will have to wait to find out.
Can you tell me more about the beta blood test? Why is it the best option?
The beta blood pregnancy test or a quantitative hCG test will test the amount of hCG in your blood. hCG can be detected in the blood as early as 8-9 days after ovulation/fertilization (shortly after implantation).
At least two blood draws are required for this test to be accurate if you’ve had an hCG trigger. The first draw gets a baseline hCG level, and a second level is drawn two days later. If the hCG level increases, it can mean you are pregnant. If the level decreases, it could mean the test is detecting the hCG from the injection, and you may not be pregnant. Another blood draw can be done in two days to see if the hCG is still rising or still decreasing.
Using HCG strips to “test” for pregnancy…
If you’re not into getting your blood drawn or if you just can’t wait for blood tests, there is another way! A method called “testing out” can be used to see how long the hCG lasts in your body. Following the hCG trigger shot that induced ovulation, then start using a home pregnancy test (HPT) or hCG strips every day (or twice daily, depending on how obsessed you are feeling) and watch as the lines get lighter. When the line is getting lighter, it means the hCG is leaving your system (there is less in your urine to test).
When the line disappears or gets extremely faint, this tells you how long the hCG stays in your body. When the line comes back or starts getting darker again for a couple days in a row, you could be pregnant!
At this point, you would want to call your doctor and make an appointment for the beta blood test to confirm the pregnancy.
As I have already addressed in a previous blogpost, several other factors need to be considered when testing out the shot. First, it is very important to use the same brand of HPT or hCG strip. Each brand can differ in color and sensitivity. By using the same brand the whole time, you will be able to see the pattern better. Another factor is the concentration of your urine (how hydrated you are). Testing right away in the morning when your urine is typically the most concentrated is the best time. When we start talking about accuracy, we must keep in mind that HPTs aren’t designed to be used for accuracy. They are, however, meant to provide a “yes or no” answer. When you get that positive test, try not to set your hopes too high (which is easier said than done), and make an appointment to get your blood drawn to confirm the pregnancy.
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