Unveiling the Mysteries of hCG

by Pregnancy.org Staff

What Is HCG

calling for resultsIf you are like most women, even the mere thought of "Am I or am I not pregnant" can be a period filled with anxiety and/or excitement as you await a clear answer either way. Detective hats in place, we have tracked down and unmasked the one that can give you a definitive response -- a hormone called human chorionic gonadotropin; more commonly referred to as hCG. This hormone is made by cells that help form the placenta. It is present at each and every pregnancy, with production beginning as soon as the fertilized egg attaches to the uterine walls.

How Soon Can I Know If I'm Pregnant?

If you are in a hurry to learn that life changing "yes" or "no," you will need to opt for a blood test. hCG can be measured within a normal blood sample approximately 11 days after conception. Those a few days further along can have their hCG detected within a urine sample. The latter is what the majority of home pregnancy tests measure.

Your pregnancy test isn't positive yet? Don't worry! Some women don't produce enough hCG to trip a pregnancy test until two weeks after they've missed a period.

In general the hCG level will double every 48 to 72 hours. The levels will reach their peak in the 8-11 weeks of pregnancy (the third month) and then will decline and level off for the remainder of the pregnancy.

What About Those Numbers

The table below shows typical hCG values during pregnancy. These numbers are merely guidelines. Every woman's hCG levels may rise differently. It is not necessarily the level that matters but rather the amount of hCG increases during early pregnancy.

HCG Levels by Week
3 weeks LMP 5-50 mIU/ml
4 weeks LMP 5-426 mIU/ml
5 weeks LMP 18-7,340 mIU/ml
6 weeks LMP 1,080-56,500 mIU/ml
7-8 weeks LMP 650-229,000 mIU/ml
9-12 25,700-288,000 mIU/ml
13-16 weeks LMP 13,300-254,000 mIU/ml
17-24 weeks LMP 4,060-165,400 mIU/ml
25-40 weeks LMP 3,640-117,000 mIU/ml
Non-pregnant females <5.0 mIU/ml
Postmenopausal <9.5mIU/ml

My hCG Levels Are Low

Don't panic just yet. Certainly a lower result bears watching. There are a number of different possibilities in play. A low hCG level could mean you have irregular cycles or longer cycles than average or you could ovulate later in your cycle. Your baby is really younger than the 28-day pregnancy wheel predicts. Unfortunately, for some, low levels could indicate an ectopic pregnancy or a possible miscarriage. Finally, there is also the chance you might be one of those women with a perfectly healthy pregnancy and lower hCG levels as your "norm." The only way to know for sure is to test again within a few days and compare the results to obtain a clearer picture on what may be happening with your baby and body.

My High hCG Levels Are High

Ah, this result could be exciting! A higher level of hCG might mean your baby is a little older than predicted. Maybe you ovulated earlier than you thought, or maybe that "strange cycle" was actually implantation taking place. Then there are those odds that you could be having twins! One negative option is a high level could possibly indicate a molar pregnancy, but know that is rare. You might simply be one of those women with a perfectly healthy pregnancy and higher hCG levels as standard for your body. Again, to help definitively know what is going on, you can have these checked again and evaluate the difference.

Should My hCG Level Be Monitored?

In most cases, your medical caregiver will opt to wait things out. It generally is not common for doctors to re-check your hCG levels unless you are showing signs of a possible problem. A health care provider may re-check your levels if you are bleeding, having severe cramping or have a history of miscarriage. For those with higher levels, a follow up ultrasound can tell you whether you will need to plan for two (or more!) additions to your family.

What Could Interfer with hCG Levels?

Nothing should interfere with an hCG level except medications that contain hCG. These medications are often used in fertility treatments and your health care provider should advise you on how they may affect a test. All other medications such as antibiotics, pain relievers, contraception or other hormone medications should not have any affect on a test that measures hCG.

What Can I Expect of My hCG Levels After a Pregnancy Loss?

First off, please know we are very sorry for your loss. To answer the question, most women can expect their levels to return to a non-pregnant range about 4-6 weeks after a pregnancy loss has occurred. This can differentiate by how the loss occurred (spontaneous miscarriage, D & C procedure, abortion, natural delivery), and how high the levels were at the time of the loss. Health care providers may continue to test hCG levels after a pregnancy loss to ensure they return back to <5.0mIU/ml.

Key hCG Facts

An hCG will definitely say whether you are pregnant and if you get two done about 48 hours apart, comparing the results can also indicate if the pregnancy seems to be progressing normally. But the hCG level cannot tell you how far along you are, as women's values vary tremendously in normal pregnancies.

• Two types of tests: A qualitive hCG tests looks to see if hCG is present. A quantitive or beta hCG test measures how much hCG is present. HCG is measured in mIU/ml.
• HCG level doubles: In 85% of normal pregnancies hCG levels double every 48 to 72 hours. As you get further along into pregnancy and the hCG level gets higher, it may take 96 hours or more for your results to double.
• Don't obsess. A normal pregnancy may have low hCG levels and deliver a perfectly healthy baby. The results on an ultrasound after 5-6 weeks gestation are much more accurate than using hCG numbers.
•Positive and negative results: An hCG level of less than 5mIU/ml is considered negative and anything above 25mIU/ml means you're pregnancy.
• hCG levels should not be used to date your pregnancy since these numbers can vary so widely.
• Correlations between ultrasound and hCG levels: Your transvaginal ultrasound show at least a gestational sac once the hCG levels have reached between 1,000-2,000mIU/ml. Because levels can differentiate so much and conception dating can be wrong, most technicians recommend a diagnosis should not be made by ultrasound findings until the level has reached at least 2,000mIU/ml.
• A single hCG reading doesn't give enough information for most diagnosis. When there is a question regarding the health of your pregnancy, multiple hCG test done a couple days apart provide more reliable information.

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