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During pregnancy, you will experience a change in many of your hormone lab values. But did you know by the 10th week of pregnancy, your hCG levels could be as high as 170,409 mIU/mL? This is a large number considering your starting hCG level was probably 0!
Why and how does hCG increase so rapidly?
hCG levels double approximately every 48 hours for the first 6-7 weeks of pregnancy. This is known as hCG doubling and is important to maintain a healthy pregnancy.
Since hCG is vital for a healthy pregnancy, you may be wondering about your levels. Or maybe you’ve been on one too many TTC forums, and now you’re convinced you’re having twins based on your hCG level!
In any case, we will review everything you need to know about hCG doubling during pregnancy. We’ll cover what hCG levels are normal and possible causes of abnormal hCG levels.
First, let’s review why hCG is important during pregnancy.
Importance of hCG in pregnancy
Human chorionic gonadotropin (hCG) is also known as the “pregnancy hormone” and it plays a crucial role in maintaining a healthy pregnancy. The main role of hCG is stimulating the corpus luteum to produce progesterone. Progesterone is also an essential hormone that helps maintain a healthy pregnancy.
Progesterone and hCG both play a vital role in pregnancy. And to confirm if you are pregnant, you must take a pregnancy test.
When you take a pregnancy test, whether at home or the doctor’s office, it is testing for the presence of beta hCG. Hormones such as hCG, LH, FSH, and TSH are made up of alpha and beta subunits. The alpha subunits are identical for each hormone. Their beta subunits are what give them their unique characteristics. This means beta hCG is more specific.
Beta hCG tests can be qualitative or quantitative.
- Qualitative test– tests for the presence of hCG (think at-home urine test)
- Quantitative test– tests for how much hCG is present
At-home pregnancy tests can confirm pregnancy. If more than 20 mIU/mL is detected, you’ll receive a positive pregnancy test. But only blood tests can help determine if a pregnancy is going as expected. hCG levels must be tracked and trended. One hCG test will not give you an accurate illustration of how your pregnancy is going.
Serial hCG levels will clue you into if you’re experiencing the following:
- Healthy pregnancy
- Ectopic pregnancy
- Molar pregnancy
- Miscarriage
hCG levels are also measured in non-pregnancy-related cases such as ovarian, bladder, and testicular cancer.
So what should you expect your hCG levels to be during pregnancy?
Normal hCG levels in pregnancy
Once your baby nestles itself into your uterine lining (implantation), the placenta starts to secrete hCG. The starting level of hCG is usually 0 mIU/mL.
From here hCG values should double every 48 hours during the first 6-7 weeks of pregnancy. hCG doubling time is correlated to the viability of the pregnancy. If hCG is not increasing at an expected rate, there could be an issue.
Note- as pregnancy progresses, the doubling time slows down. Your hCG levels will not continue to double every 48 hours for all of your pregnancy. Can you imagine how high your hCG levels would be if they did?
Take a look at the hCG doubling time chart below. You can see a wide range of what is considered normal hCG levels by week.
hCG levels rise rapidly and peak around week 10 of pregnancy. From here, levels plateau.
Again, the numerical value is not as important as the rate at which the levels increase.
The highest rate of increase is seen during the first couple of days after implantation. You can see in the table below that hCG levels in the urine are shown to increase 3-fold two days after implantation!
Importance of hCG doubling
hCG doubling in the first 7 weeks of pregnancy signals that your pregnancy is developing normally. hCG that rises outside of this range could signal an underlying problem.
The following are a few possible causes if hCG is rising slower than expected:
- Ectopic pregnancy- a pregnancy that occurs in a location other than the uterus (eg. the fallopian tubes, the ovaries, etc.)
- Impending miscarriage
- Anembryonic pregnancy- this is a pregnancy where a gestational sac is present but there is no embryo detected on ultrasound
Here are a few possible causes if hCG is rising higher than expected:
- Multiple pregnancy- twins, triplets, quadruplets, oh my!
- Molar pregnancy- this is a rare type of complication of pregnancy that results in a noncancerous mass/tumor. Sometimes a fetus is present at the beginning of the pregnancy and miscarries, sometimes there is no fetus at all. The “cluster of grapes” mass secretes high levels of hCG.
- You may be farther along in your pregnancy than predicted.
If hCG values are declining, then unfortunately the pregnancy is non-viable and will end in a miscarriage.
Learn more: HCG and Miscarriage: What do they mean?
Please note- while hCG doubling is the standard, not all women will experience it during a healthy pregnancy.
Some women will have hCG levels that increase at lower levels. Studies show the minimum increase should be 66% for a viable pregnancy.
hCG alone does not paint the whole picture of whether a pregnancy is viable. One study showed if hCG alone is used to predict the risk of miscarriage, the accuracy was only 44.72%. Other tests should be used such as ultrasound or blood tests along with hCG for confirmation
How can I make sure my hCG levels keep doubling?
You cannot control your hCG levels. There’s no DIY or home remedy to increase your levels.
If there is an underlying problem affecting your hCG levels, you should work closely with your OB/GYN to address the issue.
Key Takeaways:
- hCG doubles approximately every 48 hours during pregnancy for the first 6-7 weeks.
- hCG levels reach their peak at around week 10 of pregnancy. After this, they plateau.
- Low hCG levels could indicate miscarriage, ectopic pregnancy, or anembryonic pregnancy
- High hCG levels in pregnancy could indicate multiple gestation or molar pregnancy.
- Declining hCG levels signal a nonviable pregnancy.
- hCG levels may rise at a lower rate and still result in a successful pregnancy.
- There is no supplement or home remedy to ensure hCG doubling.
FAQs
Can you have a successful pregnancy with slow-rising hCG levels?
Yes, in some cases your hCG levels will rise more slowly and you will go on to have a successful pregnancy. The minimum level that hCG levels need to rise is 66% over 48 hours.
Does high hCG mean less chance of miscarriage?
High hCG and doubling hCG does not mean you have a lesser chance of miscarriage. There’s a huge range of what is considered a normal hCG level. This means the value does not matter as much as the rate at which your values are increasing. Miscarriage becomes a concern when your hCG levels decline or are not rising at the expected rate.
How quickly does hCG rise after implantation?
hCG levels rise at an accelerated rate after implantation. hCG levels are shown to increase 3 fold in the first few days. Usually around 1.6-3 fold during the first week. Interestingly, the day of implantation might affect your hCG levels and how quickly they rise. hCG may rise quicker if implantation occurs early (7 DPO or earlier). If implantation occurs later (10 DPO or later), hCG levels tend to be lower. However, this is not a reflection of the viability of your pregnancy.
What hCG level indicates miscarriage?
One hCG level cannot determine if you are having a miscarriage. Declining hCG levels, however, likely will result in a miscarriage. If you are worried about your hCG level or you think you might be having a miscarriage, consult your doctor.
When does hCG stop doubling?
hCG doubling begins to slow down around 6-7 weeks of pregnancy. And after week 10, hCG levels plateau.
Should I take hCG supplementation or progesterone supplementation?
Since the main role of hCG is to stimulate the corpus luteum to make progesterone, you may wonder if you should take a progesterone supplement. Women have been given progesterone for luteal phase support in IVF and embryo transfer, but many experienced side effects. hCG supplementation is a viable alternative in such cases. hCG after intrauterine insemination (IUI) has been shown to improve pregnancy outcomes.
How often should I check my hCG levels?
In a healthy pregnancy, hCG levels are not checked regularly. However, if there are concerns with your pregnancy or your hCG levels are abnormal, then your doctor may want to track your levels. hCG blood tests may be repeated after 2-3 days to ensure hCG is rising at an acceptable rate.
Do hCG levels change daily?
During the first 10 weeks of pregnancy, your hCG levels change daily. Approximately every 48 hours your hCG levels will double in value.
What does it mean if my hCG levels are doubling but I’m bleeding?
hCG doubling is a positive sign your pregnancy is developing at a normal pace. Bleeding during pregnancy can be benign or may indicate an underlying condition. Please consult your OB/GYN if you are bleeding during pregnancy.
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