Human chorionic gonadotropin (hCG) is a hormone produced by the placenta during pregnancy. It helps thicken a person's uterine lining to support a growing embryo and tells the body to stop menstruation. HCG levels rise after conception and continue to rise until about 10 weeks in pregnancy.
After about 8-10 weeks, hCG levels begin to fall, and they eventually stop progressing.
After your hCG level passes 6,000 mIU/ml, it may take more than 4 days to double. You can usually expect your hCG level to stop rising between week eight and week 11 of pregnancy. That is the time period during which the hormone tends to reach its peak.
HCG levels rise quickly and exponentially, usually doubling every 2 days3,4 in the first weeks before reaching a steady level (plateau) around week 10, after which time they slowly decline.
hCG levels usually consistently rise until around week 10–12 of your pregnancy, when the levels plateau or even decrease. This is the reason why pregnancy symptoms can be greater in the first trimester and ease off after this time for many women. In early pregnancy, hCG levels usually double every two to three days.
Every patient with an HCG level greater than 10,800 mIU/ml had a visible embryo with a heartbeat.
If your hCG levels aren't exactly doubling but are still increasing, that's a good sign. Because of these natural variations, hCG patterns alone cannot determine whether or not your pregnancy is viable. Hormone testing should always be followed up by an ultrasound before a diagnosis is made.
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.
Sometimes, hCG levels drop, but then rise again and the pregnancy continues normally. Although this is not common, it can happen.
Although not common, dehydration can cause spotting in pregnancy. It's believed some women experience spotting when dehydrated, as their hCG levels temporarily stop increasing, or dip. Once re-hydration is reached, hCG levels level out and spotting may stop.
While knowing hCG levels may be helpful, it is not an absolute indicator that a person will experience pregnancy loss. The risk of pregnancy loss is greatest in the first trimester, which coincides with rising hCG levels.
In general, however, if the hCG levels are dropping in the first trimester, this probably is a sign of impending miscarriage. On the other hand, slow-rising hCG levels that do not double every two or three days in early pregnancy may be a sign of problems, but can also occur in a normal pregnancy.
But many miscarriages also had hCG levels above this threshold; 50 IU/L did not discriminate well between ongoing pregnancies and miscarriages. A higher threshold of 135-147 IU/L performed better. Nearly 94% of pregnancies with hCG levels above this threshold were ongoing.
A slow rate of rise or a drop in HCG levels during the first 8 to 10 weeks of pregnancy represents death of trophoblastic tissue and can indicate ectopic or nonviable intrauterine pregnancy. Serial quantitative HCG values are, therefore, helpful in management of threatened early pregnancies.
It typically takes from one to nine weeks for hCG levels to return to zero following a miscarriage (or delivery). 1 Once levels zero out, this indicates that the body has readjusted to its pre-pregnancy state—and is likely primed for conception to occur again.
When your body is showing signs that you might miscarry, that is called a 'threatened miscarriage'. You may have light vaginal bleeding or lower abdominal pain. It can last days or weeks and the cervix is still closed. The pain and bleeding may resolve and you can go on to have a healthy pregnancy and baby.
If your hCG levels fall below the normal range, it's not necessarily a cause for concern. Many women have gone on to have healthy pregnancies and babies with low hCG levels. Most women don't ever have cause to find out what their hCG levels are specifically.
From the time implantation occurs, hCG levels soon begin to soar, increasing by almost 60 percent every 48 hours, give or take. The rapid increase peaks somewhere between 7 and 12 weeks after your last period, and then starts to decline.
hCG levels that are slow rising or level off before eight weeks can indicate an ectopic pregnancy. An ectopic pregnancy is an abnormal pregnancy where the embryo implants outside of the uterus, usually in the Fallopian tube. It is important to remember that the rate of hCG increase varies widely between women.
The hCG hormone level in the blood doubles every 48-72 hours. If the hCG level doubles well, this indicates that the cells of the embryo are dividing well, suggesting that the pregnancy is progressing normally and is healthy.
After 22-24 weeks, a viable pregnancy is when a baby has a chance to survive outside of the womb. However, some countries without adequate neonatal care consider a pregnancy to be non-viable at less than 26-28 weeks gestation.
That said, hCG levels vary from person to person and pregnancy to pregnancy, so hCG levels are not definitive to determine a twin pregnancy. Some people have high hCG levels and only give birth to one baby; others have exceptionally low hCG levels and give birth to multiples.
In 15–20% cases out of 100 pregnancies, the fetal heartbeat is not detected within 6 weeks of internal sonography. The situation can be very depressing because couples who have conceived but there's no fetal heartbeat, such couples begin to panic as they generally interpret it as a pregnancy loss.