Human chorionic gonadotrophin is the embryonic hormone that ensures the corpus luteum continues to produce progesterone throughout the first trimester of pregnancy. As well as maintaining progesterone production from the ovary, human chorionic gonadotrophin may also play a role in making sure the lining of the uterus endometrium is ready to receive the implanting embryo. Recent studies have indicated that human chorionic gonadotrophin may help to increase the blood supply to the uterus and be involved in re-shaping the lining of the uterus in preparation for the implanting embryo.
Human chorionic gonadotrophin is produced by the trophoblast cells which surround the developing embryo at approximately day five of pregnancy. The amount of human chorionic gonadotrophin in the bloodstream doubles every days as development of the embryo and placenta continue, and levels peak at around six weeks of pregnancy.
Following this peak, levels of human chorionic gonadotrophin fall although they remain detectable throughout pregnancy. Once the placenta is established, it becomes the main source of progesterone production around week 12 of pregnancy , and human chorionic gonadotrophin is no longer required to maintain ovarian function. However, human chorionic gonadotrophin may have additional beneficial effects in the latter stages of pregnancy; such roles are currently being investigated by researchers.
There is no strong evidence that high levels of human chorionic gonadotrophin cause direct negative consequences. Most tests use lines to show when a test is positive. The test line does not have to be as dark as the control line to be positive.
Any line at all indicates the test is positive. Test strips can change color as they dry. Some people notice an evaporation line after several minutes. This is a very faint line that may look like a shadow. An individual must check the test within the time frame the instructions indicate, usually 3 minutes.
Tests read after 10 minutes may be inaccurate or show evaporation lines. Learn more about evaporation lines here. HCG tests are more likely to produce false negatives than false positives. The longer after implantation a person waits to do the test, the more accurate it will be. HCG levels begin rising when an embryo implants in the uterus. Implantation usually happens a week or so after ovulation. It can take several days for HCG levels to rise high enough for a test to detect the hormone.
Due to how long it takes for HCG levels to rise, it is possible for a woman to be pregnant and still get a negative test. A positive result usually appears after retesting a few days later. False-positive results are rare. However, because home pregnancy tests are increasingly sensitive, some can detect very early pregnancies with low HCG levels.
This sensitivity means it is possible to have a positive test that a very early miscarriage then follows. A woman who delayed testing or who used a less sensitive test might not have known about the miscarriage. Pregnancy, Birth and Baby is not responsible for the content and advertising on the external website you are now entering. Video call. This information is for your general information and use only and is not intended to be used as medical advice and should not be used to diagnose, treat, cure or prevent any medical condition, nor should it be used for therapeutic purposes.
The information is not a substitute for independent professional advice and should not be used as an alternative to professional health care. If you have a particular medical problem, please consult a healthcare professional. For more information, please visit the links below:. You are welcome to continue browsing this site with this browser. Some features, tools or interaction may not work correctly. There is a total of 5 error s on this form, details are below.
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In a man or a nonpregnant woman, a high hCG level can be a sign of a tumor cancerous or noncancerous. These tumors can develop from a sperm or egg cell germ cell tumor , such as a tumor of the testicles or ovaries. It may also mean some types of cancer, such as cancer of the stomach, pancreas , large intestine, liver, or lung. Low values If you are pregnant, a low level of hCG can mean an ectopic pregnancy or a miscarriage. It may also mean that you aren't as far along in an early pregnancy as you thought, based on your last menstrual period LMP.
If you are pregnant, levels of hCG that are going down abnormally can mean a miscarriage spontaneous abortion is very likely. What Affects the Test You may not be able to have the test, or the results may not be helpful, if: You do your urine test for hCG very early in pregnancy during the first week after implantation or on a urine sample taken in the middle of the day. The test may not always show an early pregnancy.
You have had a miscarriage spontaneous abortion or therapeutic abortion. HCG results may stay high positive for up to 4 weeks after a miscarriage or therapeutic abortion. You got an injection of hCG to treat infertility. This may cause test results to appear high for several days after the injection. There is blood in the urine sample or soap in the collecting container.
These can change the hCG level. You use diuretics or promethazine. These medicines can cause false low hCG levels in urine test results. You use heparin, a medicine to prevent blood from clotting anticoagulant.
You use certain medicines. These include hypnotics such as Ambien , antipsychotics, and antinausea medicines such as prochlorperazine. Be sure to tell your doctor what medicines you take.
To learn more, see the topic Home Pregnancy Tests. A blood test for hCG is generally more accurate than a urine test. If you still think you're pregnant even after your urine test results do not show a pregnancy negative results , you can try a blood test.
Or you can repeat the urine test in a week. A normal hCG value does not rule out the possibility of a tumor in the uterus, ovaries, or testicles. HCG is only one part of a group of tests when a tumor is suspected.
Screening for fetal chromosomal abnormalities. Obstetrics and Gynecology , 1 : — Manual of Laboratory and Diagnostic Tests , 8th ed. Philadelphia: Lippincott Williams and Wilkins. Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed.
Louis: Mosby Elsevier. Wapner RJ, et al. Prenatal diagnosis of congenital disorders. In RK Creasy et al. Philadelphia: Saunders Elsevier.
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