hCG Levels by Week: What You Need to Know

Team Peanut
Team Peanutlast year4 min read

You’ve learned about lots of hormones while trying to conceive — estrogen, progesterone, luteinizing hormone… the list goes on! Now that you’re pregnant (yay!), maybe you thought your hormone class was over, right? Not so fast. Once you conceive, a new hormone comes into play: human chorionic gonadotropin, or hCG. What is hCG, and how does it affect your pregnancy? And what are normal hCG levels by week? Let’s find out!

hCG Levels

In this article: 📝

  • What Is hCG?
  • Why is hCG important?
  • hCG Levels Week by Week
  • What else can hCG tell us?

What Is hCG?

hCG is Human chorionic gonadotropin, often referred to as a “pregnancy hormone” because it’s at its highest levels during pregnancy. It is produced by the placenta after the fertilized egg implants in your uterus. Fun fact: a pregnancy test works by detecting hCG in your urine.

Why is hCG important?

When you get pregnant, hCG helps to build up the lining of your uterus (making a cozy home for your fertilized egg) and tells your ovaries to stop ovulating.

A rapidly increasing hCG level, especially in the first trimester, is a good sign of a developing embryo. Likewise, low hcg levels in pregnancy could indicate some potential issues, including possible miscarriage.

hCG Levels Week by Week

What week of pregnancy does hCG show up?

hCG becomes detectable in urine about 10 days after ovulation. This could be considered “week 4” of pregnancy. (Week 1 starts the first day of your last period.) hCG levels at 4 weeks pregnant are ideally about 5 to 426 mIU/mL (that’s units per milliliter of blood).

What is a normal hCG level at 5 weeks?

After implantation, pregnancy hormone levels should start to rapidly increase, doubling every couple days. hCG levels at 5 weeks should be about 19 to 7,340 mIU/mL. As you can see, it’s a big increase from week 4! And it just keeps getting bigger. hCG levels at 6 weeks will increase to around 1,080 to 56,500 mIU/mL. Wow, that placenta is really working!

If you’re wondering what normal hCG levels are during pregnancy, you can look at an hCG levels chart by week, like this one from the

hCG levels chart

You can see that the hormone level goes up and up and up until about week 12, then it starts to decline. The decline might be one reason that morning sickness tends to ease up at the end of the first trimester.

What else can hCG tell us?

There is a huge range of normal hCG levels during each stage of pregnancy. High or low numbers could be totally normal, or could indicate an issue.

Low hCG levels

Some women have lower levels or their levels don’t increase as quickly as they “should,” but their pregnancy is still perfectly healthy. Sometimes a low hCG level just means that you’re earlier in pregnancy than you thought.

But sometimes a low hCG level or especially a decreasing level can be a sign of a miscarriage. If you’re having bleeding or other miscarriage symptoms, your doctor might test your hCG levels to see what is going on. If you’re wondering, At what hCG level will I miscarry?, there’s unfortunately no clear-cut answer to that question.

Your doctor will look at the trend in your levels to make a diagnosis.

High hCG levels

High hCG levels could mean that you’re farther along in pregnancy than you thought. It could also mean — surprise! — you’re having twins!

If you get a positive on a pregnancy test very early, like 8 days after ovulation, that might mean your hCG levels are very high due to a multiples pregnancy. But the only way to be sure you’re having twins is to get an ultrasound. And if you are having twins, you might want to look at an hCG levels chart by week, like this one.

High hCG levels could also indicate other extremely rare issues, like a tumor or a molar pregnancy. A healthcare professional will be able to guide you if you have any concerns.

Well, now you can add hCG to your vastly expanding knowledge of all things pregnancy. There are so many changes going on in your body, inside and out. Wherever you are in your pregnancy journey, you’re doing a great job!

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