Pregnancy is filled with a lot of internal changes. As a woman, you’re told that your hormone levels are going crazy with hormones you didn’t even know that you had. At such high levels, you’re feeling moody, agitated and sad all at the same time.
One of the first things that your doctor will check are your hCG levels.
Before we go into immense detail about this hormone, we want you to have a clear understanding of what hCG does, and why it’s starting to show up on your blood tests now that you’re pregnant.
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What Are HCG Levels?
So, what are hCG levels anyway?
Human chorionic gonadotropin (hCG) is a hormone that is found only when pregnancy occurs. This hormone is actually produced by the placenta. When you get pregnant, the placenta is formed to nourish the egg after fertilization.
The job of the placenta is very important. It allows for:
- Nutrition: The placenta transfers maternal blood with nutrients and oxygen to the fetus. This is how the baby is effectively “fed” when inside the womb.
- Excretion: Waste products of the fetus are removed by the placenta. This is normally urea and uric acid.
- Immunity: The mother’s immunity to certain illnesses will be transferred through the placenta to the baby between weeks 20 and 24.
All of these important functions take place from the placenta itself. The function that produces hCG is the endocrine function. This is when the placenta starts to produce hormones that are very important for the baby during pregnancy – and the mother of course.
Secretion of hCG begins early on after pregnancy because it plays a direct role in the fetus’s growth. As an organ, the placenta can be rejected by the body. This rejection would end the pregnancy. The hormone hCG suppresses this immunologic response from the body so that the placenta is allowed to remain and provide nutrition to the fetus growing inside of you.
In short, hCG is formed so that the placenta is not rejected by the mother’s body.
Note: This hormone is not found in a non-pregnant woman’s body in high amounts. hCG is the same hormone used by pregnancy tests to determine if a woman is pregnant.
Appropriate levels of hCG are less than 5 mIU/ml in non-pregnant women, and when levels are 25 mIU/ml or higher, a woman will be considered pregnant.
Normal HCG Levels
When a woman is not pregnant, she will not have hCG levels detected. Remember, this hormone is only produced by the placenta, so “normal” really doesn’t exist since hCG isn’t present in the body.
However, once pregnancy hits, this is completely different.
HCG Levels During Pregnancy
The hCG hormone levels will start being seen on blood tests 11 days after implantation. This isn’t a hard and fast rule, so it may take a woman’s body a little longer or shorter to start producing the hormone in sufficient levels for it to be detected on a blood test.
If hCG levels are being detected through urine, the hormone levels will not be high enough for detection until days 12 – 14.
During pregnancy, the levels of the hCG hormone will skyrocket before leveling off.
HCG Levels by Week
Week-by-week, the hormone levels will nearly quadruple. This occurs due to the hormone levels doubling nearly every 48 – 72 hours, or 2 – 3 days. This will not continue throughout the entirety of the pregnancy. While 85% of pregnancies will follow this frequency, some women will have much lower levels of hCG being produced, so there is no norm.
In fact, it will eventually level off, but we’ll discuss that more in depth shortly.
Doctors won’t check hCG Levels by day simply because they’ll fluctuate so much in the beginning. Normally, the levels will increase by 33% per day for the first 8 – 11 weeks of pregnancy.
Doctors are not concerned with this hormone as much because it’s used mainly for detection of pregnancy.
As the pregnancy moves along, it can take 96 hours for the level of hCG in the body to double. This occurs close to the time when the hormone will eventually begin to level off, and there are sufficient hormone levels in the body to stop the rejection of the placenta and allow for a full-term pregnancy.
hCG Levels at 4 Weeks
A great way to understand just how rapidly these levels increase is to look at weeks 4 and 5 during pregnancy. During week 4, the average hCG level is 75 mIU/ml; this is when a missed period has just occurred.
By the end of week 4, the amount of hCG in the body will be 1,940 – 4,980 mIU/ml.
All of this occurs in just 7 short days and will be when you’ve just missed your period in most cases.
hCG Levels at 5 Weeks
The start of week 5 will begin with hCG levels of 2,580 – 6.530. This is a very important week in terms of pregnancy development because a few days into the 5th week, the yolk sac will be formed. This normally occurs 3 days into the 5th week of pregnancy.
By the time week 5 comes to an end, hCG levels will be between 10,140 and 23,340. If you remember, we started week 4 with just 50 – 100 mIU/ml of hCG detected. This is a very huge jump in the amount of hCG in the body, but it won’t remain this high forever.
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hCG Levels as Pregnancy Progresses
Your doctor will have an hCG level chart, also called a beta hCG chart, available. While these charts used to be used to determine how far into a pregnancy a woman is at the current time, it is generally accepted that the variance in hCG levels prediction is highly inaccurate. This chart becomes irrelevant when ultrasounds are used and right after the determination of pregnancy.
Every chart is slightly different because every woman is different, so the figures will vary greatly.
- Week 4: 50 – 4,980 mIU/ml
- Week 5: 2,580 – 23,340 mIU/ml
- Week 6: 11,230 – 65,380 mIU/ml
- Week 7: 36,130 – 112,870 mIU/ml
- Week 8: 64,600 – 116,310 mIU/ml
Many important phases occur during this time. During week 5, the yolk sac forms and the baby starts developing. Within just 4 days, the baby already has a heartbeat that occurs during week 6. The 6th week is also the time when the embryo is seen and normal development will continue from here.
Between weeks 9 and 10, the hCG levels will start to decrease.
Eventually, the amount of hCG will reach a plateau where it will stay for the duration of the pregnancy. There is no exact number seen at this time.
What Do Low hCG Levels Mean?
What happens if my hCG levels are low?
This is a question that a lot of young mothers-to-be ask their doctors. Normally, it’s advised to wait 48 – 72 hours and conduct a retest. This, as you already know, will allow the amount of the hormone to double in the body so that levels rise once again.
If, at this point, the levels are still low, it can mean one of three different things:
- Miscalculation of pregnancy dating
- Ectopic pregnancy
If you’re relying on a pregnancy test, you will want to consult with your doctor immediately at this point. There is a chance that miscarriage occurred, which would stop the production of hCG in the body.
What Happens if My Levels Are High?
Another common question. Hormone levels are elevated for a variety of reasons. A molar pregnancy or a miscalculation may be the cause. Another possibility is that you may be pregnant with more than one baby, which would cause the amount of hCG needed by the placenta to be much higher.
hCG Levels After Miscarriage
Sadly, some pregnancies end in a miscarriage, and your body will stop producing the hCG hormone. You will not immediately see the hormone levels go back to pre-pregnancy levels. Instead, the process takes 4 to 6 weeks in most cases.
The level of hCG in the blood at the time of pregnancy loss can be used to determine how the loss occurred. The levels would be different depending on the cause of the miscarriage.
In the event of a miscarriage, doctors may want to continually check your hCG levels. This is done so that the doctor can ensure the hormone levels return to less than 5.0 mIU / ml. If the levels do not return to normal, further testing may be needed to determine why hCG levels are not returning to normal.
Medications can also cause hormone levels to deplete, but this will depend on the medication and will need to be discussed with your physician.
The body, more precisely the placenta, will start to produce the hCG hormone so that the body does not reject the placenta. This plays a vital role in pregnancy and is often the most used technique in over-the-counter pregnancy tests to determine whether pregnancy has occurred. hCG will play a major role in child birth and the levels can double in 2 to 3 days after eventually tapering off later in the pregnancy.