During the first trimester, levels of hCG should double every 48 - 72 hours with the levels reaching between 50,000  300,000 mIU/ml at the end of the first trimester. After the first trimester levels of hCG drop dramatically with the levels remaining well above the base level of 5 mIU/ml throughout the pregnancy.
http://www.baby2see.com/preconception/hcg.html
However, after an embryo or fetus stops growing and a miscarriage occurs, the hormone does not disappear from a woman's body right away. The level of hCG gradually decreases, falling back down to zero over a period of days or even weeks depending on how far along the pregnancy was when the miscarriage happened.
https://www.verywell.com/positive-pregnancy-after-a-miscarriage-2371516
The hCG levels will usually double approximately every 48 hours [ 2 days ] for the first four weeks of pregnancy. As pregnancy progresses the doubling time increases. By 6 to 7 weeks gestation beta hCG levels may take as long as 84 hours [ 3½ days ] to double.
http://www.baby2see.com/preconception/hcg.html
A molar pregnancy is the result of a genetic error during the fertilization process that leads to growth of abnormal tissue within the uterus. Molar pregnancies rarely involve a developing embryo, and the growth of this material is rapid compared to normal fetal growth.
http://americanpregnancy.org/pregnancy-complications/molar-pregnancy/
Home tests are sometimes done too soon after the missed menstrual cycle to result in a positive test. It typically takes 10 days after a missed menstrual period before the presence of hCG can be detected by the urine test. All urine hCG tests should be done on a first morning urine sample, if possible.
https://labtestsonline.org/understanding/analytes/hcg/tab/faq
Quick Answer. According to Mayo Medical Laboratories, the level of human chorionic gonadotropin will fall to half of its pregnancy concentration in the body within 24 to 36 hours of birth, miscarriage or abortion. From this half-life speed, normal levels should be achieved within roughly one or two weeks. Continue Reading.
https://www.reference.com/health/long-after-delivery-hcg-levels-back-normal-ecd5cf52e884364a
A Word From Verywell. Experiencing a miscarriage can be an emotional rollercoaster and the confusion over a persistently positive pregnancy test can add to this already difficult situation. Be assured though that it can take a variable amount of time (on average two weeks) for a woman's hCG level to disappear after a miscarriage.
https://www.verywell.com/positive-pregnancy-after-a-miscarriage-2371516
How many days after a miscarriage would it take for a urine pregnancy test to show a negative result? Urine hCG decreases at about the same rate as serum hCG, which can take anywhere from 9 to 35 days, with a median of 19 days. However, the timeframe for when an hCG result will be negative is dependent on what the hCG level was at the time of the miscarriage.
https://labtestsonline.org/understanding/analytes/hcg/tab/faq
Some normal pregnancies will have quite low hCG levels and still progress, ending in the birth of a healthy baby. The best way to confirm if a pregnancy is progressing is to repeat with a blood test in 2 to 3 days time, and perhaps again 2 to 3 days after that.
http://www.baby2see.com/preconception/hcg.html
Molar Pregnancy: Symptoms, Risks and Treatment. A molar pregnancy is an abnormality of the placenta, caused by a problem when the egg and sperm join together at fertilization. Molar pregnancies are rare, occurring in 1 out of every 1,000 pregnancies.
http://americanpregnancy.org/pregnancy-complications/molar-pregnancy/
when do hcg levels disappear after birth
HCG, Human Chorionic Gonadotropin levels disappear after birth within 24 to 36 hours. Human chorionic gonadotropin levels disappeared from 24 to 36 hours after a birth.