How beta hCGs grow in the various weeks of pregnancy

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Beta hCg as they grow in pregnancy

Let's tackle a topic that seems to me very interesting and important, also based on the many questions I receive on the forum about the topic: beta-hCg pregnant. Let's see how these hormones grow during the various weeks of pregnancy and what they tell us about the progress of gestation.

In this article

  • What are beta hCGs
  • When to do the dosage? Beta hCG when to do them?
  • Beta hCG at week 4
  • Beta hCG negative
  • Beta hCG valori
  • Beta hCG with low values
  • Beta hCG and twin pregnancy
  • Beta hCG in an ectopic or ectopic pregnancy
  • Beta hCG old

What are beta hCGs

It is a hormone present only in pregnancy (and in some very particular and rare tumor pathologies which however are not our topic today) whose full name is human chorionic beta-gonadotropin.

  • The production takes place from the first weeks of pregnancy by a particular tissue called trophoblast from which with the progress of the weeks the placenta will develop, or the exchange organ (of oxygen and nutrients) between the mother and the baby. It is the blood or urine dosage of this hormone that gives us the positivity of the pregnancy test. I say blood and urinary because the same hormone can be found in both sites with different concentrations and characteristics.
  • The detection of beta-hCg in the urine with the common test turns out to be a little more difficult at the beginning of pregnancy, because its concentration varies greatly depending on, for example, the time of day, the distance from the last urination and again from the amount of fluids taken that dilute the urine.
  • La presence of the hormone in the blood is instead more constant because it is not influenced by external factors and can therefore be easily identified even very early and above all more reliable.
Read also: When to take the pregnancy test

When to do the dosage? Beta hCG when to do them?

Depending on the method chosen, there could be two different times. However, my advice is always to wait for the lack of menstruation. Let's take an example, if you have a regular cycle and on the 28th day there is no menstruation, on the 29th day it is possible to proceed with the blood dosage. In reality, in the blood, at least in most cases, beta-hcg also appears a few days earlier, around the 25-26 day of the cycle, but to avoid false negatives I always recommend waiting.

As far as the dosage in the urine instead, my suggestion is to wait a few more days. That is, allow 4-5 days to pass from the lack of menstruation, and carry out the detection in the morning on the first urine, after it has remained in the bladder for at least 3 hours. Therefore, whatever the method chosen, it will give you a result in a short time (within the day for the blood test) and very short times (a few minutes for the urine test). These results should be interpreted as a first value, which should be confirmed and reassessed if the obstetrician or gynecologist requests it.

Beta hCG at week 4

If we calculate that to do the test we have to wait for the lack of menstruation we will arrive at the dosage around 4 gestational weeks, calculated from the first day of the last menstruation (always referring to a hypothetical regular cycle). We must consider a positive test when the dosage exceeds the value of 10 mU / ml (the magnitude means milliunits per milliliter of blood or urine). Modern urine tests based on this principle are able to calculate approximately at what week of gestation you are reporting it on the display. The same principle applies to the blood dosage, the results of which will also report the reference values ​​for the gestational period. At the time of detection, ie at 4 gestational weeks this value should have risen and be understood between 2160 and 82640.

Beta hCG negative

What if the measured value is less than 10? Attention to this detail, we are talking about regular cycles in which ovulation occurred with extreme probability between the 14th and 16th day of the cycle. If the cycles are irregular or simply longer, the speech made before must be modified a little. In fact, if ovulation occurs later, the appearance and relative detection of the beta-hcg hormone in the blood and urine will also be delayed. Therefore, the timing of the test must be adapted to the personal situation. Possibly what I recommend is to carry out a first dosage, if it is negative, wait 5-6 days and repeat the dosage to evaluate the situation. What I can assure you is that with an ongoing pregnancy it is impossible for the test to be negative. There may be variations in times and dosages depending on the characteristics of the cycle and fertilization, but it cannot be negative.

Beta hCG valori

The trend in the value of Beta hCG follows, on average, a growth of this type: it doubles every 2 days for values ​​up to 1200 IU (international milli-units per milliliter); double every 3 days for values ​​from 1200 IU to 6000 IU double every 4 days for values ​​above 6000 IU. And if between a withdrawal and the other the growth in values ​​is particularly high, it could be one twin pregnancy, but each pregnancy is unique and a high value could in any case also correspond to the gestation of a single embryo.

Here is a table ofthe values ​​of Beta hCg for weeks from conception (mean values).

The first number is the week of pregnancy, the second is the minimum value and the third number refers to the maximum value of the betas:


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Beta hCG with low values

The determination of a low or high value of the hormone is always made with respect to standard reference values ​​and is related to a specific gestational age, i.e. a value may be low for a week but within the norm for the previous one. I made this premise because many times the data detected by the beta-hCG dosage is taken as an absolute data on the progress of pregnancy. Not so, it must be related to the menstrual history and ultrasound results.

  • Let's take our 4-week dosage for example. If less than 2160 it would appear that the pregnancy is not progressing well, but if the conception occurred later than expected (and it can happen) it is normal that the value is lower and simply because it is smaller.
  • Then there is another case in which it is not easy to determine if the values ​​are actually low, and that is that of medically assisted fertilization (IVF, ICSI, IUI etc.). In this case we know when the conception took place but we do not know exactly when the body will accept the pregnancy and then start the production of beta-hCG. Very often the values ​​in these cases are below the norm. For example, a small study showed that in the case of IVF after 14 days from the embryo transfer (therefore about the 4th week) values ​​of 300-600 indicated 50% of pregnancies in progress.
  • There are unfortunately unfortunate reasons why beta-hcg can be low and they are: miscarriage and detention, and ectopic or extrauterine pregnancy. In the first case it happens that a pregnancy that may have begun has not continued and therefore there is a failure to increase the value, which in reality will decrease and halve within 24-48 hours until it is completely zeroed. The case of deemed abortion (i.e. when the embryo or parts of the components of the gestational chamber are not expelled despite the absence of the heartbeat) is the typical case in which the beta-hCG remain present without however having a normal growth. In fact, the mere presence of part of the pregnancy tissue leads to the continuous production of the hormone, however not sufficient to be able to affirm that the pregnancy is proceeding correctly. Confirmation will then take place with the execution of an ultrasound to identify any remaining tissues.

Beta hCG and twin pregnancy

The first and most common cause of above-normal dosage of beta-hcg is the presence of a twin pregnancy. In fact, the trophoblast will produce a greater amount of beta-hCG in order to develop the components necessary for each child. So values ​​above 82640 at 4 weeks shouldn't be surprising if there are two or more babies. The more children there are, the more likely it is that beta-hcg is elevated relative to the gestational age.

Read also: What is the trophoblast

Beta hCG in an ectopic or ectopic pregnancy

Ectopic pregnancy is a pregnancy that occurs in a different location than the correct one, i.e. in places other than the uterus. It is often referred to as extrauterine that pregnancy that is positioned in the fallopian tubes or in any case inside the pelvis, while ectopic that occurs in the abdomen. The second case is not very common, while the first is easier. The reasons are different and not all known: for example, there may be an obstruction of the entrance to the uterus or of the reasons why the fertilized egg does not pass.

It is a condition that should not be underestimated because it puts a woman's life at risk, pregnancy is made to establish itself in the uterus, where it can erode the mucosa, implant and grow. In other places this cannot happen because if it happens it causes severe inflammation and bleeding that expose to hemorrhages. Also in this case the beta-hCG will grow slowly, because the trophoblast tissue cannot develop that much and will always remain below the norm compared to the gestational period. Normally if there is only the suspicion of ectopic pregnancy, ultrasound and removal are immediately carried out to avoid the risks I mentioned earlier.

Beta hCG old

High beta-hCG dosages: There is also the opposite case, which is that beta-hCG can be high. Leaving aside the fact that obviously if the gestational period is underestimated (i.e. if it is believed that the week of pregnancy is lower than it really is) the value found will be above the norm, I would analyze the two most common cases in which the dosages they can be elevated.

  • as we have seen, one of the possible causes of a high Beta value is an ongoing twin pregnancy.
  • Another case, a little less happy, is the condition called hydatiform mola, or vesicular mola. It is an abnormal form of pregnancy in which fertilization actually takes place but an embryo does not develop, but vesicles that take on a cluster shape. Clearly the pregnancy will fail but the beta-hcg will still be produced and detected. Values ​​of beta-hCG greater than 100.000 at 11 days from conception can lead to suspect the presence of vesicular mola. The diagnostic suspicion will then be confirmed through an ultrasound which will reveal the presence of the vesicles in the place of the embryo, for which we will proceed with the scraping.

In conclusion, what I want to emphasize is that the dosage of the beta-hcg hormone is definitely the first step to understand if you are pregnant. From that moment on it can be a useful parameter to understand the progress of pregnancy but it cannot be the only one. We have seen several cases in which beta-hCG goes up or down and it is therefore essential to correlate the value with the results of other instrumental tests, first of all ultrasound.

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