Everything You Need to Know About hCG Levels

If you’ve ever taken a pregnancy test, hCG is the hormone that’s measured to see if you’re pregnant. Additionally, hCG is a key indicator as to how your pregnancy is developing – and it can pinpoint any potential complications, e.g. an ectopic pregnancy or blighted ovum.

Knowing the role of hCG in your body when you become pregnant allows you to understand how your pregnancy is progressing, and what to expect as your hCG levels change over time.

What Is hCG?

hCG stands for human chorionic gonadotropin. It’s formed and secreted by your placenta after implantation.

These hCG levels begin to rise and encourage the production of progesterone by sending a message to your corpus luteum. The corpus luteum is a temporary structure that develops in your ovaries during pregnancy to produce high levels of progesterone. In turn, the higher levels of progesterone support your growing embryo by preventing the shedding of your uterine lining. For this reason, you may hear the signals of hCG being referred to as, “the rescue of the corpus luteum.”

A pregnancy test uses what’s known as a sandwich enzyme immunoassay technique to detect rising changes in your hCG hormone.

How Does a Pregnancy Test Work?

While this technique may sound incredibly complicated, it truly isn’t.

There are two main components to hCG: an alpha and beta part. A pregnancy test contains two special antibodies that detects both parts. If you’re pregnant when you urinate onto the stick, the antibodies will sandwich the hCG between them. This triggers the dye that creates the positive dark line on the pregnancy test. The second line is simply an indication as to whether these antibodies are working.

What hCG Levels are Normal?

An hCG level above 25mIU/mL tends to indicate a positive pregnancy, while negative results are anything below 5mIU/mL. Levels of hCG are first detected approximately 11 to 14 days after conception by a blood or urine test.

In typical cases, hCG levels double every 2 to 3 days until they peak after 8 to 11 weeks. Then, they will drop off before plateauing for the rest of your pregnancy. Likewise, it’s no coincidence that the period during which your hCG level rises is often when morning sickness occurs.  

However, it’s important to note hCG numbers themselves shouldn’t hold too much weight. Sometimes low values of hCG are normal during pregnancy. Rather, it’s the doubling of the hormone that’s more important.

Your hCG levels are only monitored through a serial beta hCG test if your pregnancy is:

·         high risk

·         occurs after a number of miscarriages

·         compromised by severe cramping or some bleeding

What Do Low Levels of hCG Indicate?

There are a few potential causes of low hCG levels – something your doctor will be able to investigate and discuss with you further.

• Miscalculated Conception Date: It can be incredibly difficult to pinpoint the exact date of your conception. While it technically begins as soon as implantation occurs, most doctors will work from the day you missed your last period. If you’re unsure of when you last ovulated, the anticipated hCG levels and pregnancy date might be inaccurate. In these cases, ultrasounds are more accurate.
• Ectopic Pregnancy: If your hCG levels are rising sporadically or they’re not rising as they should be, there’s a possibility the pregnancy is ectopic (i.e. happening outside of the womb, often within a fallopian tube). Medical attention is essential in these cases. While it isn’t possible to save the baby, the potential ruptures an ectopic pregnancy may cause can have a serious impact on your health.
• Blighted Ovum: When a fertilized egg doesn’t become an embryo, this type of miscarriage occurs. While your hCG levels may have triggered a positive pregnancy test, they’re not likely to rise any further and will instead stay low. These miscarriages are often caused by a chromosomal abnormality, which happens completely by chance. However, the odds of getting pregnant again are relatively high.

What Do High Levels of hCG Indicate?

In contrast, high hCG levels may indicate entirely different causes, including:

• Miscalculated Conception Date: As before, a high level of hCG could be due to the inaccurate calculation of your date of conception – you may be further along than your doctor first thought!
• Molar Pregnancy: This occurs when there are defective cells in your placenta. These cells continue to secrete hCG as they grow around a non-viable embryo or grow too fast. High blood pressure, high hCG levels, and heavy bleeding during early pregnancy can all point toward a molar pregnancy. Medical professionals will be able to assess whether this abnormal cell growth needs removing or not.
• Multiple Pregnancy: Also, higher hCG levels may indicate you’re carrying multiple embryos. You could soon be welcoming twins, triplets, or more into the world!

Checking these higher levels every 2 or 3 days to see if anything changes is very important.

What Happens to My hCG Levels After Pregnancy Loss?

Approximately 4 to 6 weeks after losing your pregnancy, your hCG levels should start to return to their pre-pregnancy range. The time and type of loss (natural delivery, abortion, D & C procedure, or spontaneous miscarriage) can cause a differentiation in how long it takes your levels to return to normal.

To ensure the levels return to < 5.0mlIU/mL, many healthcare providers will continue to monitor your hCG levels for several weeks after your pregnancy loss.

What Can Interfere with My hCG Levels?

If your pregnancy test indicates a positive result, it’s highly likely you’re pregnant. It’s extremely rare to get a false positive. However, some conditions can result in these false readings, including early miscarriage and certain types of cancer. Also, some types of antibodies can affect the results.

Medications used for fertility treatments that contain hCG may also interfere with your hCG levels. All other types of medication, e.g. contraception, pain relievers, antibiotics, and hormone medication shouldn’t affect an hCG test.

Monitoring Your hCG Levels

While home pregnancy tests are incredibly accurate and can detect higher-than-normal levels of hCG, they’re unable to indicate your exact hCG levels.

Generally speaking, you should expect the lines on your pregnancy test to get darker the further along you are in your pregnancy. However, testing too often can lead to negative results, as there hasn’t been enough time for the hCG to accumulate in your urine.

Ultimately, hCG is a great indicator of successful conception and can be used to effectively monitor the progression of your pregnancy. Thankfully, routine checking of your hCG levels won’t be necessary unless doctors want to monitor for any potential complications.