Low (or Slow Rising) hCG Levels – What It Means for Your Pregnancy

by Aug 12, 2021

If you’re familiar with home pregnancy tests, you’re likely familiar with the hormone human chorionic gonadotropin.  Also known as hCG or beta hCG, this is the hormone released mainly during pregnancy and used by home pregnancy tests to determine a positive result.

As early pregnancy progresses, hCG levels typically follow a predictable pattern of increasing with some notable deviations and changes.  In this post we’ll look at what it means to have slow rising hCG and what it could mean for your pregnancy.

The role of hCG in pregnancy

Also known as the pregnancy hormone, hCG is produced by the cells surrounding a developing embryo that eventually go on to form the placenta.  Production of this hormone kicks in almost immediately after implantation and levels increase rapidly during the early weeks of pregnancy.

After implantation occurs and hCG starts to be produced, the corpus luteum continues to produce progesterone throughout the first trimester of pregnancy.

Without progesterone, the womb lining would shed and prevent an embryo from implanting.  hCG makes sure this doesn’t happen by ensuring the corpus luteum continues progesterone production until the placenta is established and can take over production.

In addition to triggering progesterone production and aiding fetal growth, hCG also supports other bodily functions over the course of a pregnancy.  It promotes the development of new blood vessels in the uterus as well as smoothing the muscle cells in the uterine wall, both critical developments for maintaining a pregnancy.

Normal hCG levels

Human chorionic gonadotropin is produced naturally by the pituitary gland and occurs in both males and females throughout their lives.  However, because of its key role in pregnancy, hCG production is at its highest during the first trimester of pregnancy and typically follows an exponential rise.

 
 
 
 
 

In early pregnancy, hCG levels continue to rise until the last weeks of the first trimester, or around the 9-12 week mark.  Standard levels can vary from woman to woman and will depend on a number of factors including how your body reacts to pregnancy and the number of embryos you are carrying.  A woman carrying more than one embryo will usually have a higher baseline level of hCG than one carrying a single embryo due to the hormone’s role in fetal development and early pregnancy.
Typically, hCG levels double every 48 to 72 hours for the first four weeks of a normal pregnancy, then slows to every 96 hours by week 6, and peaks around 10 weeks, before leveling off and remaining constant for the remainder of the pregnancy.

During the weeks that follow implantation, these standard hCG levels serve as a guideline for the normal range in each week of pregnancy.  However, it should be noted that levels vary from woman to woman and will entirely depend on what’s normal for you, how your body reacts to pregnancy, and whether or not you are carrying multiples.

Because a single measurement won’t provide trend information, multiple hCG tests may be needed to confirm whether your levels are increasing at the appropriate rate.  There are reasons for slow rising hCG levels and numbers and doubling times are not the only indicators of trouble or concern.  In a low-risk pregnancy, checking hCG doubling times is not normally needed and is usually only reserved for cases where there are underlying concerns such as previous miscarriages.

Typical hCG levels vary widely from woman to woman but as long as they are in the normal range and rising steadily, there should be little concern.  Home pregnancy tests work by detecting a threshold of hCG in urine but only exact levels can be determined with a blood test.

The table below gives the range of expected levels (measured in milli-international units of hCG hormone per milliliter of blood (mIU/mL)).

Pregnancy Week (weeks since last menstrual period)
Standard hCG Range
Non-pregnant 0 – 5 mIU/mL
3 weeks 5 – 50 mIU/mL
4 weeks 5 – 426 mIU/mL
5 weeks 18 – 7,340 mIU/mL
6 weeks 1,080 – 56,500 mIU/mL
7-8 weeks 7,650 – 229,000 mIU/mL
9-12 weeks 25,700 – 288,000 mIU/mL
13-16 weeks 13,300 – 254,000 mIU/mL
17-24 weeks 4,060 – 165,400 mIU/mL
25-40 weeks 3,640 – 117,000mIU/mL

 

Low hCG levels

Low hCG levels are not always a cause for concern.  Although the doubling guideline holds true in 85% of normal pregnancies, not all pregnancies follow this pattern and almost 8% of viable intrauterine pregnancies exhibited a slower rate of hCG rise.  Your doctor will likely keep a close eye on these levels throughout the first trimester, but it’s important to remember that this isn’t the only tool they will use to monitor your pregnancy.

What do low hCG levels mean?

During early pregnancy, hCG monitoring is valuable for assessing the health and status of a pregnancy.  Because typical hCG levels can fall in a wide range, your doctor is more concerned with how your levels change – are they rising or not – and the rate of change rather than the actual number.

Low or slow rising hCG levels can mean several things and could indicate a number of possible scenarios.  A Low beta hCG result could mean that the date of your pregnancy was miscalculated and you are not as far along as you thought.  If you have irregular periods, aren’t tracking your cycle, or are unsure of the dates then it’s possible you miscalculated and further tests will be needed to determine gestational age.

Slow rising hCG levels could also be a sign of other problems in the pregnancy that may result in pregnancy loss.  If a pregnancy fails to progress, initial levels may have appeared normal but failed to rise on subsequent tests.  This type of result may indicate you have had or will have a miscarriage.  Falling hCG levels can be a sign of miscarriage but will often be accompanied by other symptoms such as cramping, bleeding, and passing tissue or clots.

In addition to miscarriage, low or slow rising hCG levels could indicate a blighted ovum or ectopic pregnancy.  Although different conditions, they both involve the development of a fertilized egg and therefore hCG hormone.

A blighted ovum, when the fertilized egg attaches to the womb but doesn’t develop, usually occurs early in pregnancy and many women may not even know it has taken place.  Symptoms may appear as normal menstruation and you’ll likely think it’s your period.

An ectopic pregnancy may be a dangerous and life-threatening condition where the fertilized egg remains in the fallopian tube but continues to develop.  As an ectopic pregnancy progresses, it is usually accompanied by a range of physical symptoms that indicate a problem such as severe abdominal pain, heavy bleeding, and dizziness or shock.  Low or slow rising hCG levels can be a sign of an ectopic pregnancy but your doctor will order more than hCG tests alone for this type of diagnosis.

It’s important to remember that low or slow rising hCG isn’t in and of itself an indication of pregnancy problems.  A small but significant percentage of pregnancies continue without complications, even with low hCG levels.

Can you get pregnant with low hCG?

A successful pregnancy is still possible even with low or slow rising hCG levels.  This is especially true since levels differ greatly between women and even between pregnancies.  If a complication with hCG levels has occurred in the past, there is no indication someone will be unable to get pregnant again.

What can cause hCG levels?

Although ranges vary, hCG levels are driven by the development of a pregnancy.  Because of the wide range, it can be difficult to determine what is considered a high level.  High levels of hCG may mean you’ve miscalculated your pregnancy date, you’re carrying multiples, or may be the result of fertility drugs.

Although doctors aren’t usually concerned by high levels for these reasons, in rare cases high hCG levels may indicate a serious complication known as a molar pregnancy or chromosome abnormalities of an embryo.  Molar pregnancies are a rare abnormality where a non-viable egg implants in the uterus and develops as a non-cancerous mass rather than a fetus.

Is it possible to increase hCG levels?

Although it may be tempting to try and find ways to increase your hCG levels, it simply can’t be done.  There is no way to change or make your levels go up nor should you want to.  Your hCG levels, and the way they change, can give valuable information about the health of your pregnancy.  Artificially changing those numbers, by trying to increase hCG levels, would only mask potential problems rather than indicate them.

Low hCG and miscarriage

Unfortunately, one of the reasons for slow rising hCG could be a miscarriage.  If your hCG levels fail to rise or even go down, your doctor may be concerned about the viability of the pregnancy.  Other blood tests may be ordered and your doctor will likely want to perform a transvaginal ultrasound to check for any other issues.

If your hCG levels don’t come close to doubling or decrease from previous measurements, it’s likely an indication that the embryo is no longer developing and the pregnancy is not viable.  Since the embryo has stopped developing, the body is no longer producing hCG to support fetal growth and tests will reflect that.

Low levels of hCG do not necessarily indicate a miscarriage, and should be used as a baseline to help track the change over time.  However, if your levels are dropping, the outlook is rarely good and declining hCG levels after a positive pregnancy result mean chances are high the pregnancy is nonviable.

Tracking hCG levels

A blood test is the most accurate way to detect and track hCG levels and home pregnancy tests detect the hormone but can’t tell you the amount of hCG in your urine .  And while some pregnancy tests on the market are geared to tell you if your hormone levels have risen over the baseline, they are not meant to monitor healthy pregnancies.

Fertility tracking systems, like Mira Fertility Plus, can help you track other fertility hormones like luteinizing hormone and estrogen.  Tracking and monitoring these hormones can help you achieve your fertility goals and provide valuable health information about your body.  Ultimately your healthcare provider will determine if you need to track your hCG levels and will explain the results in more detail.

✔️ Medically Reviewed by Katerina Shkodzik, M.D., OB-GYN

Dr. Katerina Shkodzik is a certified OB-GYN with a special focus on reproductive endocrinology and infertility issues. She has been practising since 2015.

Dr. Shkodzik completed her residency program in the Department of OB/GYN at the Belarusian State Medical University and fellowship program in the Department of Gynecological Surgery at the Medical University of Bialystok, Poland.

Dr. Shkodzik is extensively involved in digital health projects providing her medical expertise and integrating of cutting edge technologies in medical science and clinical practice since 2018.

Dr. Shkodzik has participated in several studies focused on PCOS, endometriosis, menstrual cycle characteristics and their abnormalities based on big data of digital health in collaboration with leading universities.

She believes that paying special attention to women's health is a crucial step to improving the world we live in.

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