Human Chorionic Gonadotropin: Normal Levels of hCG Concentration During Pregnancy
No matter if they are at their first baby or they were pregnant before, many women have heard of the term human chorionic gonadotropin or hCG, while they were trying to conceive or soon after birth, but didn`t really know what it means.
Table of Contents
What Is hCG & When It`s Produced?
Human chorionic gonadotropin is a hormone that is secreted by the developing embryo`s special shell while pregnant. Human chorionic gonadotropin supports the normal development of pregnancy. Because of this particular hormone, the body of a pregnant woman blocks the processes which cause menstruation and the hormone production required to maintain the pregnancy. Human chorionic gonadotropin is produced very early during pregnancy, and serves to several functions in helping the fetus to develop, as well as stimulates the production of estrogen and progesterone.
Human chorionic gonadotropin is composed of 2 parts: the alpha and beta subunits. The alpha subunit of hCG is very similar to other hormones in the organism, and the beta subunit is unique. Thus, hCG analysis consists of determining the concentration of the beta subunit in blood or urine.
Small amounts of hCG are produced by the pituitary gland, even in the absence of pregnancy. This explains that in some situations, low levels of hCG hormone in blood are also found in women who aren`t pregnant (women at menopause as well) and even in men`s blood.
Since the beginning of pregnancy, the baby will pass through several stages of development. The woman`s egg along with the man`s sperm will unite to form the zygote. The zygote will pass through a quick division process, forming the trophoblast. This will start to secret hCG since this early stage of pregnancy, but this won`t happen before the implantation of the baby in the womb. The ovulation and fertilization will usually appear around the 14th day, starting with the first day of menstruation. If the fertilization will occur, the zygote will pass through the fallopian tube to the uterus. At around 7 to 9 days after fertilization, the baby will be implanted deep into the uterus.
Read more on What Is Oxytocin And What Is Its Role In Childbirth?
This hormone is produced in the outer layer of the placenta. Its role is to make a connection between the mother`s blood and the fluids of the embryo. The mother`s organism won`t start to produce hCG until that moment. After the production of the hormone starts, this can be tracked by pregnancy tests.
The Importance of Human Chorionic Gonadotropin
This hormone helps maintain the pregnancy for a woman until the second trimester of pregnancy, when the placenta starts to function fully and takes control. It also helps with the creation of testicles, estrogen secretion and placental development.
Women, who have experienced infertility issues or who have had miscarriages, will have their doctors take blood samples to check their levels of hCG 2 or 3 times per week in early pregnancy.
This is mostly because human chorionic gonadotropin should be at least double in a period of 48 hours, until it reaches a certain level, and then drops. If the level is indeed double, it`s a sign that the pregnancy is viable and is progressing normally.
If only a small increase in this hormone level or no increase occurs, this might be the first sign which a doctor or midwife can use to notice if the pregnancy will go over the first trimester or not.
There is no norm in the normal interval of hCG levels during a pregnancy. The general values are shown in the following table.
|Week from the date of the last menstruation||The amount of hCG in ml|
|3||5 – 50 (less than 5 means you aren`t pregnant|
|5||19 – 7340|
|7 – 8||7650 – 229000|
How Does hCG Change during Pregnancy?
In case of a normal development of pregnancy, Human chorionic gonadotropin can be determined in the blood of the pregnant woman, around 8 to 14 days after conception.
The level of hCG increases rapidly, starting with week 3 of pregnancy, and doubles at each 2 or 3 days. The increase of the concentration in the blood of pregnant women continues until around 11 – 12 weeks of pregnancy. Between the week 12 and 22 of pregnancy, the concentration is slightly reduced. From the week 22 until birth, the concentration of hCG in the blood of a pregnant woman starts to increase again, but much slower than in early pregnancy.
Taking into consideration the rate of increase in hCG concentration in blood, doctors may identify some deviations from normal pregnancy development. In particular, during ectopic pregnancy or a pregnancy that was stopped from evolving, the increase of the concentration is slower than during normal pregnancy.
Read more on Taking Progesterone to Get Pregnant!
Accelerating the rate of increase in the hCG concentration might be a symptom of hydatidiform mole, multiple pregnancy or fetal chromosomal malady (e.g. Down syndrome).
There`s no strict norm of the hCG content in the blood of pregnant women. The levels of human chorionic gonadotropin, during the same period of pregnancy, may be different from one woman to another. In this regard, the unique measurements of human chorionic gonadotropin are a little informative. To assess the process of pregnancy development, the dynamics of changing the concentration in blood is important.
Normal Concentrations of hCG depending on the Pregnancy Term
|Days since the last menstruation||The pregnancy term||The standard of hCG level for this period, mU / ml|
|26||12 days||0 – 50|
|27||13 days||25 – 100|
|28||2 weeks||50 – 100|
|29||15 days||100 – 200|
|30||16 days||200 – 400|
|31||17 days||400 – 1000|
|32||18 days||1050 – 2800|
|33||19 days||1440 – 3760|
|34||20 days||1940 – 4980|
|35||3 weeks||2580 – 6530|
|36||22 days||3400 – 8450|
|37||23 days||4420 – 10810|
|38||24 days||5680 – 13660|
|39||25 days||7220 – 17050|
|40||26 days||9050 – 21040|
|41||27 days||10140 – 23340|
|42||4 weeks||11230 – 25640|
|43||29 days||13750 – 30880|
|44||30 days||16650 – 36750|
|45||31 days||19910 – 43220|
|46||32 days||19910 – 43220|
|47||33 days||27470 – 57640|
|48||34 days||31700 – 65380|
|49||5 weeks||36130 – 73280|
|50||36 days||40700 – 81150|
|51||37 days||45300 – 88790|
|52||38 days||49810 – 95990|
|53||39 days||54120 – 102540|
|54||40 days||58200 – 108230|
|55||41 days||61640 – 112870|
|56||6 weeks||64600 – 116310|
Exceeding the Normal hCG Levels too Much Indicates a Multiple Pregnancy
If the human chorionic gonadotropin level is checked and isn`t only double, but even triple or 4 times more, it`s often a symptom that there`s more than 1 baby in the uterus.
When a woman is pregnant with more children, her hormones will grow much faster than they do when it comes to just one pregnancy.
If you have questions regarding your level of hCG, talk to your doctor about it. He`s the only one who can test it correctly and offer health-related answer while pregnant.