Human Chorionic Gonadotropin is what hCG stands for, but what is it? It’s a hormone, it’s a fascinating science, it’s what gives you a positive pregnancy test, it’s what kicks those early pregnancy symptoms into gear, and it’s not actually that complicated to understand. So let’s dig in and explore what hCG levels do and how they relate to pregnancy.
In this article, we’ll cover some key information about hCG levels, including:
- What are hCG levels?
- What are normal hCG levels?
- What it means if your hCG levels are high or low
- Plus, how often hCG levels are checked during pregnancy
What Are hCG Levels?
In order to fully understand hCG levels, let’s take a look at the earliest stages of pregnancy. Once the egg is fertilized by the sperm, the cells of the egg undergo immediate changes, with cells dividing and dividing, quickly growing into what is called the embryo. The layer of cells that surround the embryo is what produces the hormone human chorionic gonadotropin (hCG). As the embryo continues to grow, these same cells that produce hCG eventually form into the placenta, which embeds itself into the wall of the uterus.
In normal conditions, hCG signals to the body that a pregnancy is underway, and acts to nourish and protect the developing life. HCG also kickstarts all those lovely first signs of pregnancy—tender breasts, nausea, and fatigue, to name a few!
How Early Can hCG Be Detected?
This is a common question, because hCG is what at-home pregnancy tests are testing for, and hCG levels can give you information about how your pregnancy is developing.
HCG levels rise during the first trimester and can be detected in the urine as early as 7-11 post fertilization (sometimes even a little bit earlier!). HCG can also be detected via a simple blood test, which is usually how your healthcare provider confirms your pregnancy.
How Quickly Should hCG Levels Rise?
As early pregnancy progresses, hCG generally doubles every 48 hours, peaking around the 6th to 8th week of pregnancy. HCG levels then start decline and level off (though they are still detectable) for the remainder of the pregnancy.
What Are Normal hcG Levels?
It’s important to note that hCG levels can vary significantly between one person to the next, so “normal” levels are quite subjective but you’ll still see some predictable patterns.
If your hCG level is higher than 25 mIU/ml you’ll get a positive pregnancy test. Since levels double every 48-72 hours in the first trimester, the hCG levels should continue to rise. Though the ranges below are not absolute, it’s a good reference point for a single pregnancy. (More on twins below!)
|Days from LMP||hCG Range for Singleton Pregnancy|
|28||9.4 – 120|
|33||300 – 600|
|36||1, 200 – 1, 800|
|40||2, 400 – 4, 800|
|45||12, 000 – 60, 000|
|70||96, 000 – 144, 000|
What Happens If My hCG Levels Don’t Fall Within the “Normal” Range?
Remember, these numbers are just rough guidelines.
If you are low-risk and there is no concern about the viability of your pregnancy, some providers won’t even test your hCG levels at all. Other providers may test once to make sure your levels appear to be in a “normal” range.
If hCG levels don’t fall within the normal range, your doctor or midwife will likely request a blood test to check your hCG. Here’s what you can expect:
- You will have an initial blood test to check hCG levels.
- A few days later, you will have a follow-up blood test to see if your levels are rising or falling. (Note: It is common to have as many as 2 to 4 blood tests to measure hCG when trying to diagnose a possible pregnancy complication.)
- If the levels are going up, then pregnancy is advancing; if the levels are going down, it could indicate a possible miscarriage, or you could be further along in your pregnancy than you thought. If you take a peek at the chart above, you will see that hCG starts to decline after 13 weeks or so.
Do You Have hCG Levels When Not Pregnant?
Though most women do not have measurable hCG levels when not pregnant, it is possible to have hCG in your body when not pregnant. This can create a false positive on a pregnancy test. Luckily, this is not very common.
Let’s take a look at some of the reasons why you might have measurable hCG levels in your body:
- Chemical pregnancy: Sometimes a pregnancy occurs briefly, but results in pregnancy loss before a woman even knows she’s pregnant. Even though this loss occurred very early on, a woman may have hCG in her body because the cells around the fertilized egg produced enough of the hormone to be detected by a pregnancy test.
- Pituitary hCG: The pituitary gland is a small structure in the brain that can produce hormones that are structurally similar to hCG. This pituitary hCG can be mistaken for pregnancy hCG, but this is not very common!
- HCG diet: Who would ever have imagined this pregnancy hormone would go hand-in-hand with a weight loss program? It is not recommended, but hCG can be given by injection or ingested orally by purchasing an over-the-counter pill, spray, drops, or pellets. Combined with a very low-calorie, restricted diet, proponents say hCG “resets the metabolism.”
- Hormonal imbalance: Some health conditions that affect the endocrine system, like PCOS, germ cell tumors, and trophoblastic disease, can stimulate hCG production in people who aren’t pregnant.
What Does It Mean if Your hCG Levels Are Low?
Low hCG levels are not always a cause for concern.
It could mean that you are testing too early. Most home pregnancy tests have about the same ability to detect hCG, but their ability to show whether or not you pregnant depends on how much hCG you are producing.
Your body begins producing hCG around 7 to 10 days after conception, and pregnancy tests don’t guarantee accuracy until about 11 days after conception. Wait a couple of days and retest if you suspect you may be pregnant.
And some women just have low hCG levels. It’s not common, but some women don’t produce enough hCG to ever get a positive home pregnancy test. If you suspect that you are pregnant, but you are not getting that positive pregnancy test, check in with you doctor for further testing.
Unfortunately, in some cases, low hCG levels can indicate a problem with the pregnancy. Check in with your healthcare provider if you’re concerned about your hCG levels, and try not to lose hope before you’ve completed all the recommended tests.
If hCG levels continue to be low or decline significantly, your doctor or midwife may suspect the following:
- Miscarriage: If the embryo does not properly develop to form a placenta and a viable fetus, or if the fetus dies, than it is not possible for hCG levels to rise.
- Blighted ovum: A common reason for an early miscarriage, this happens when a fertilized egg, which starts the process of producing hCG, never actually forms into an embryo. Again, if a placenta never forms, hCG levels will never rise.
- Ectopic Pregnancy: This is when a fertilized egg implants outside of the uterus, typically in a fallopian tube, but occasionally in the abdomen. These types of pregnancies are never viable. In fact, if you suspect an ectopic pregnancy, call your doctor or midwife right away—an ectopic pregnancy can be very dangerous, as it could result in a fallopian tube rupture and cause hemorrhaging.
I know personally how devastating miscarriage is. Give yourself plenty of TLC, seek help if you need it, and know that most women will go on to have healthy pregnancies in the future.
What Does It Mean If Your hCG Levels Are High?
More commonly, when hCG levels are high, it usually means that your pregnancy is a little further along than you initially thought. Repeat testing for levels, coupled with an ultrasound, will help you determine where you are at in your pregnancy.
Here are couple more reasons why you might have high hCG:
- Twins: If there are two or more babies developing, a woman will generally have higher than normal hCG levels. (More on this below!)
- Molar pregnancy: This rare complication of pregnancy results when there is an abnormality in development following fertilization. This abnormality can result in a very large placenta, a fetus that dies early on in pregnancy, or a placenta with no fetus at all. In any of these situations, the cells are forming abnormally, similar to a tumor, resulting in higher than expected hCG levels.
- Genetic conditions: Less commonly, very high hCG levels can indicate Down syndrome.
Twin hCG Levels
Though it’s not possible to identify a twin pregnancy on hCG levels alone—they vary too widely from person to person to be a definitive marker—hCG levels are generally higher in mamas carrying more than one baby. (source)
Compared with singleton pregnancies, hCG and HPL levels were respectively 2.5 and 1.5 times higher throughout gestation. (source)
|Days from LMP||hCG Range for Multiple Pregnancy|
|28||9.5 – 120|
|33||200 – 1, 800|
|36||2, 400 – 36, 000|
|40||8, 700 – 108, 000|
|45||72, 000 – 180, 000|
|70||348, 000 – 480, 000|
How Often Are hCG Levels Checked During Pregnancy?
HCG levels aren’t checked frequently during pregnancy, unless you’ve had a history of miscarriage or are currently questioning the viability of your pregnancy. If you’re low-risk and no problem is suspected, some providers won’t check hCG levels at all.
If there is concern, your doctor or midwife will recommend a blood test every two or three days to see if hCG levels are rising or falling. A single measurement of your hCG level is not useful, but rather just a starting point. To get a clear picture of what is happening in your pregnancy, a series of blood tests, a couple of days apart, needs to be taken and compared to the other values from previous testing.
Some possible reasons for having your hCG levels checked (and rechecked):
- History of miscarriage
- Your dating ultrasound and your hCG levels don’t match up
- You are experiencing severe cramping or bleeding
- History of ectopic pregnancy or blighted ovum
- Any indication that your pregnancy is not developing as you would expect in the first trimester
The science behind hCG levels and testing for the presence of this pregnancy hormone can be useful, but it has its limits. It is just one page in the book of pregnancy and doesn’t tell the whole story. If your hCG levels are higher or lower than expected, please know that your doctor or midwife will help you get to the bottom of what is happening for you and your pregnancy.
How About You?
What are your hCG levels like?